What do you mean, an example may help. 
 

Not seen this issue myself. 

I go to my Sonos app and the Sonos speakers/devices are listed but the room designations have disappeared. I reset the room designations at least weekly. 

What do you mean by “room designations”?  The name of the room?  If so, Apple Home has been known to rewrite the names of Sonos rooms if you don’t make them the same.