If I have both Channels DVR and Beta installed, under Accessibility I can see and enable "Channels Button Detector"
If I uninstall Channels DVR and only have Beta installed, I can't get to "Channels Button Detector" and enable it.
I'm getting memory constrained and need to uninstall regular Channels, anybody seen this problem and know how to fix it?
The Button Detector has been removed from beta builds to comply with Google for Play Store inclusion. When the next stable release occurs, it too will ship without the Button Detector.
This has been covered several times over the past few weeks.
Thanks for the link - didn't know - it's a shame.
The buttons still work WITHIN the app (Guide, Colors, etc...), they just don't work OUTSIDE. So all you need to do is install Button Mapper and set either the Home or DVR button (depending upon your remote) to launch the Channels App. Once the app is open, everything works as it did, no problem.
They aren't working for me within the app unfortunately. 
This is working with the Beta software Channels Beta v301160456 but not the new release version. Same Tivo 4K with Button Mapper installed.