@RJ_V There are a couple of other topics which may be helpful.
This link details a change which can be made to Apple Home settings which appears to have helped historically but last time I tried @Jeremy_Honeybun 's solution this didn’t help - I could play left or right but when grouped Roon just won’t play to the group.
This link refers to the fact that this is a known issue and currently in support (as mentioned by @beka - however I have seen this mentioned as with support before somewhere but can’t currently find it.
Hope this helps with your understanding if not your frustration… and hopefully the `Roon team will find a fix for airplay 1 used for HomePods soon.