IIRC, the Live button is oddly implemented in the TA4K's firmware in a custom manner; it is not presented as a standard remote button.
Instead of lamenting idiosyncrasies with this particular button, perhaps we should be celebrating that it has any functionality outside of TiVo's own software/apps at all.
I did read up on that. However, it is definitely being passed to Channels. After it makes it that far, Channles should be able to do what they will when responding to it. Anyone with another device and a color button mapped to Live? Does it react the same?
I have Apple TVs and have a Sony remote color button mapped to Live which brings me back to my last live channel. I have mapped that button to my One for All Streamer remote by recording the Sony's color button.
I haven't followed the details of what the button isn't doing for you, but for me it will go to the last live TV channel I watched. If you keep hitting it then it will toggle between two channels. It will not retain buffer while its doing that. Retaining buffer would be nice, but I expect that Channels isn't doing that because their tuner management isn't as robust as Tivo. If you run out of tuners, you can't on the fly tell it to release one for live TV. You'd have to into the Recordings view and stop a recording to free up a tuner. With multiple streaming devices sharing tuners on an HDHR, I expect that hanging on to buffers would make this problem a challenge to manage by potentially doubling the number of tuners being held by streaming boxes that are in live. We only have two adults in the house and with recordings I was running out of tuners with an HDHR Quatro, so ended up adding a 2nd one.
It would be nice to toggle between two stations with buffer in tact, but its not a show stopper issue for me. If I really wanted to watch two live shows and toggle between them with buffer, I'd do the following. Go to a channel from Guide. Select down arrow and hit record. Go back to Guide and select another channel. Select down arrow and hit record. Navigate to the Recordings tab. Select first show set to record to watch. Now to switch to the other show you have to hit back, then arrow to other show, then select to watch, and say resume. So its 3-4 clicks to navigate back and forth between them but if I wanted to watch two shows and miss nothing this is the only way to do it today in Channels. If I needed to do this all the time then it might be an issue, but this isn't really something I do a lot.
You have basically proved to me that the behavior I am seeing is a bug. It behaves differently for me. I think I laid it out better in this specific post (per the suggestion of another user).
If you don't mind can you post that yours doesn't work like I describe there? I know it is an Apple TV, but it is an inconsistency with how the interfaces respond.
I did work out a similar process. Yours seems to be a little better than mine. This concept has been rolling around in my head of how to ask for this as a feature that automates a lot of it. I need to learn a little more about how things work. I want to request it where it can be done as a step process where each step provides a new functionality that is easy to implement. In the end though, you wind up implementing DVR side buffers as an option. I view that as necessary for the seamless use of buffers. I don't expect it to get implemented, but I can try. 
I have a Tivo 4K too, but I lost all the button configuration when I joined their beta, so don't have the ability to test a Live Button at the moment. I will try to get a few minutes to play with it. When I tried the other day after reading your post, it seemed to be misbehaving because when I hit record on two shows to try and toggle between them in the Recording tab, neither program was showing up in the Recording tab.
One thing I will suggest, is that if there is a technically straightforward way to deal with things like this that makes sense, the developers usually jump on board with it if its not conflicting with a core design concept... like possibly not wanting to have two tuners tied up on one streaming box to maintain 2 buffers.
I tried on the Tivo after my last thread. I'll need to try and strip the Tivo stuff off of it again. When I had it setup before the update and entry into the beta, I had the Live button mapped to Channels and it worked as expected. I don't know if they have blocked the ability to strip it now... I know right after the update everyone was whining that they disabled being able to get to developer mode which was required to completely strip the Tivo stuff off. So my guess is on another Android device you could enable a Live button. I can not do it right away, but I'll try to give it a shot on one of our Sony TVs with Android TV and see if I can get the Live button working as expected. I was able to toggle between two recording shows through the Recordings tab with several clicks to go back and forth so that is working as expected.
I haven't completely stripped out TiVo, but I disabled 3 apps and rebooted (check and make sure they stay disabled). That cleared everything that needed to be cleared for me. The three apps were (from memory) Tivo Stream, com.tivo.tvlaunchercustomization, and TivoPlusPlayer. It was a simple process that got rid of all the Tivo candy and allowed Channels DVR to use the special buttons (hopefully unimpeded). I am trying to avoid setting this up with adb and other things. My rule right now with this system is that it can require configuration, but it has to be something I could talk my Wife through on the phone.
Edit: I forgot to mention that the developer options worked fine for me if I recall correctly (but I didn't wind up using them for anything). I also did order a remote to try out that will get here tomorrow.
Here is the full list of the TiVo apps that you can remove/disable to fully de-TiVo the TS4K (some are also telemetrics, tracking, and other bloatware):
com.limark.deviqcoreagentcom.nes.bugtrackercom.nes.daemonservicecom.nes.skywayclientcom.nes.tvglobalkeyhandlercom.tivo.atomcom.tivo.tivoplusplayercom.tivo.tvlaunchercustomizationcom.utsmta.appEdit: Another one might be the com.droidlogic.SubTitleService. Not quite sure what this one does, but I believe it's related to some component of the Amlogic chipset to handle some hardware overlays; however, it does tend to use a bit of constant CPU time, so it might be worth disabling if you're feeling dangerous 
Yeah, that is why I will try and suggest things that fit along the way with how things work. BTW, the particular tuner tying up thing is quite simple to manage if you do what Tivo did. Basically, if something else wants the one not being watched, then it gets it. So there is no absolute guarantee it will be there, but it takes an action to lose it. I will say that one of the harder things that helps Tivo is the concept that it is recording on all tuners all the time. I presume that is a core idea that won't come to Channels and gets very murky with TVe and different types of tuners in the system. However, I think parts of the behavior might be able to fit in.
Thanks, I might try and see what I can disable with and w/o a shell. I was mainly just try to free up the visual space and the functionality at the time. Doing the 3 "seemed" to do that.
All of them can at least be disabled, if not outright uninstalled, from the standard Android TV Settings app. There is no need to enable developer options or use ADB to disable those apps.
Did you have to enable developer mode to do that?
When I first got it, I was testing if it would be my main Channels DVR streaming box and got rid of everything including the shell required stuff. Then I determined the Apple TV was my preference and let it update, and also joined the beta which might complicate things if I try to delete stuff again. I was kicked out of the beta for inactivity because after months of updates, not a single feature was anything that I could, or that I wanted to, test. But I don't know if they still are updating my device with the beta code. After the update, I know that on TivoCommunity it appeared that they had blocked the ability to strip it like before... just curious if it can still be stripped. I'd like to give it another go.
I don't believe so, no. Although, it's been a few months since I set up a TS4K.
There some easy way to do it fully automated via a adb script with a pc.
Just google debloat or de-tivo tivo streak 4k and there is a guide on how to do it.
I donāt believe this is possible with HDHR tuners. There is no concept of forcing your way o to a tuner. If they are all used, you are out of luck.
Only 4 can be disabled from the settings app for me. The 3 I mentioned before and I can't remember the 4th. So far those other ones don't seem to cause any system issues, but possibly slow it down.
If I get a call from my wife while on travel and I can't walk her through it with just the TV remote it is unacceptable to me... If it was a device that only I was using, then fine. This is a household device.
Unless you use the DVR Server as an arbiter, which honestly is what I would be after anyways. I want all my live tv streams to come from and be buffered on the server. That way if I am in the middle of watching something and have to go, I can hit record and save it. This is not how the system works, so I don't know that it would ever get there, but it is pretty simple to manage if you make the presumption that only Channels DVR clients will be accessing the tuners.
So? u de-bloat it as your initial setup. once u do it, there's nothing more to do and the thing works as a normal google tv like device.
If you are saying you don't have physical acces to setup the device, then, thats a different thing.
But, you can't expect it to be easy, to de-tivo a TiVo device, you are going against the intended use of even buying one. TiVo wants you to use thier software.
You can't fully remove all the bloat and junk just by a long remote button pressings of "removing the apps" via the things own software menus. Some things can only be removed via adb, like the home screen locks and customizations.
You or someone here asked how to de-bloat the tivo....that is the answer...if you don't like it, DON"T BUY IT! Go buy a CCGTV.
You can force an unlock of the tuner SageTV has this option... if you choose to use it... If all tuners are in use you can have SageTV take over a tuner that is not being used by SageTV. Also if you choose to watch LiveTV and all tuners are being used by SageTV you get the option to end a recording in progress.
sagetv.device.-1043852702.always_force_external_unlock=false