I've noticed that when I turn off Tuner Sharing (simply because channel surfing is noticeably faster with my HDHomeRun that way) that the "Activity" status in Channel DVR's webUI no longer reports live viewing activity. I have two AppleTVs, both watching live local TV, each on a different channel, using Channels DVR, but the webUI reports "Idle" activity.
If I turn Tuner Sharing back on, then Activity reports the channels each AppleTV is watching.
Is this distinction intentional, by design?
Without tuner sharing, the client talks directly to the tuner. Because the DVR server is left out of the loop, it has no idea what the client or tuner are doing. If it doesn't know about the activity, it can't report about the activity.
The client could inform the server of its activities so they would be properly tracked by the DVR
That is one reason why they cannot do any type of conflict resolution among others.
Yeah, understanding now what "Tuner Sharing" actually means, and how it's implemented, this explanation makes sense. I will say though that based on very many threads here I know there's quite a bit of confusion about this setting, and what it actually means, what it does, what its pros and cons are, etc.
That said, the end result here is a bit unintuitive, that's all. I now know, that "Activity" in the webUI refers to DVR server activity only, not any client activity, and that watching a tuner with tuner sharing off, leaves the DVR out of the equation entirely. And that turning Tuner Sharing on, gets the DVR involved to share the tuners in the first place, which puts that status back into "Activity."
But prior to me having an HDHomeRun, when my only sources were TVE, prior to me even tinkering around with Tuner Sharing in the first place, the "Activity" was always 100% forthcoming about everything my AppleTV clients were doing, in relationship with Channels DVR. And now, it's not. It feels like a step backwards.
I understand this isn't a bug. I'll adjust my understanding around what "Activity" truly means. But I'd bet very many users aren't on the same page with this. Or maybe they don't check the webUI. Maybe they just don't care. 
Even with tuner sharing on there is a major bug that I have reported ... If you have multiple HDHomerun units and have tuner sharing enabled ... If each Client has a different tuner priority then tuner sharing is useless. It does not check all devices to see if the channel requested is in use.
I have several HdHomeRun units so I have to make sure that on each Client the tuner priority matches what is on the DVR which is a pain in the butt.
Tuner sharing on ...
2022/04/19 17:56:44.647818 [TNR] Opened connection to 1080ACCC/2 for ch2.1 KATU
2022/04/19 17:56:58.876514 [TNR] Opened connection to 107829D3/0 for ch2.1 KATU
This really hurts with my 2 Primes cannot really have Clients using the 2 Primes to watch the same channels.
DVR makes a lot of effort to discover HDHR devices in order not to pay attention to them. 
Simple monitoring of HDHR devices would be nice.