I've been running a large set of TiVo Stream 4K clients and would really like to take advantage of the full functionality of these mini peanut remotes as well.
After a bunch of spelunking on this, I think racameron described the current state of the expected behavior for integrated TS4K Button Detector functionality on May 1, 2022 (just above).
It looks (to me anyway) like the TS4K button remapping features for the Guide, TiVo, and Live buttons aren't working in the current (non-beta) release when the Channels app IS the foreground app. In other words if you disable the stock TS4K stuff, these three TS4K buttons don't work in Channels at all, unless you install the beta client AND enable the beta exclusive "Channels Button Detector" Accessibility Service.
Is it possible that the release version integrated TS4K Button Detector functionality that was working prior to the recent Android 10 update is now broken somehow? I'm specifically referring to the automatic TS4K remapping features for the Guide, TiVo, and Live buttons that are supposed to work by default when Channels is in the foreground (assuming I'm understanding the expected behavior here correctly).
I'm guessing this issue might have to do with the non-standard TiVo implementation of the buttons, and the hoops the channels devs probably had to jump thru to get these remappings working in the first place.
Tl;dr - It looks like the "non-beta" TS4K Guide, TiVo, and Live button remapping broke with Android 10.