Both, by voice command and via a button in google home, google doesn’t carry out a HA scene. It says, “work in proress” its waiting and after a few seconds, it says “goodbye”. I have the feeling that the scene takes too long to startup en google responds with a random reaction.
I use nabu casa. It’s installed correctly because all the scenes and devices from HA are visible in google home.
Are you using Google Routines to start the scene? If so, I’ve had a few situations where recreating the routine resolved a similar problem. In my case Google Home couldn’t decipher the command words “Ceiling fan low”. Instead of turning on the ceiling fan, Google would offer links ceiling fan websites. The problem went away when the routine was deleted then recreated.
Check the “Last Activated” column on the Scene page of HA. Does the Scene indicate that its been triggered? If not, I would think the issue lies withing Google Home.