As of a few hours ago, none of my controllers will connect to the CCU. Also starting to see a bunch of post on Redit about this issue
No issues here but you could try to reset them and resync it with the app.
https://support.google.com/stadia/answer/9584135
Another issue I had is when I tried to connect the controllers to Wifi 5G.
2.4G did work instantly.
Dont update your controller if it's still working ... Reddit posters a saying it's a bug with an update today and google is aware, but no time lines for a fix.
Ah ok... Thanks for the information!