I have 3 Google mini (working perfectly) and created several rules. No problems with them.
I added today a Google Home (better sound quality for music) into my Google home settings: NO problems (same Google user, same network). Ran the usual tasks: integrate into my network (static IP), added to my user account, listened to music (built-in and through Airfoil/BubbleUPnp (btw thanks to the guy who posted that, very nice app to swap from speakers to speakers (GM, GH, Sonos, Vizio sound bars). So, everything is OK
Added to HE: rediscovered the Chromecast integration (OK), added the new "device GuestRoom". (OK) Then I wanted to update some apps related to my group of Google devices...
To keep things simple (I'm a beginner here), my apps are: say time at 9pm, say time when a virtual button is pushed, mute them all at 11pm, unmute them all at 10am, etc.
Of course I wanted to add the new GuestRoom Google device on those existing apps.
On some, I can. On some, I can't (errors). See summarized pic.
I rebooted HE: same results
I shut down HE: same results
This is not difficult to recreate those simple tasks but I wanted to submit the problem to you, in case of.
Mike