Until a few days ago in Youtube TV going from watching a live show to the live guide, I was able to return to the live show by double clicking the play/ pause button on the Roku remote which is no longer working. Any idea why Roku disabled this function
Roku has nothing to do with how Youtube functions. You'd have to ask Google/Youtube.
This exact thing started happening to me within a couple weeks. If you switch to the guide, you can't get back the the show playing in the background by hitting play/pause twice. Does anyone know why this is happening?
All Roku can do is pass your key presses to the YouTube TV app. What the app does with them is up to however YouTube programmed the app.
YouTube is notorious for constant tinkering with their code and breaking things on one streaming platform or another (Roku, firestick, chromecast, whatever).