openhabian Pi4 4gb running openHAB 3.2.0 Build #2454
Just went through a few hours trying to figure out why some new devices wouldnt link with Google Home … previously I had 7 devices working fine I believe by using the Metadata “Google Assistant” … when I tried to add a new device it refused to show up.
I ended up removing the Google Assistant metadata and instead added with semantic class of “Point” with non-semantic tag of “Lighting” …
To be honest I have no idea which was needed or not as I haven’t gone back to play around (wasted enough time 
Just posting this here in case it helps someone else … any experts feel free to give a more definitive answer… bottom line, “Google Assistant” metadata wasn’t used in this case.
Edit: A little more detail, the category has to be “light” not “lightbulb”