I’ve seen numerous posts about this searching back over the last few years, but there doesn’t seem to be an answer or acknowledgement…
Within the past month I’ve noticed that on my Android phone (Sony Xperia 1iii running Android 12) the Roon app freezes when both of these things are true:
I cast to a Chromecast Audio device
I switch away from the Roon app to the celltop or other app and then switch back
The music continues to play and I can control playback and volume using the Google Home app, but the only way to reengage Roon is to kill the frozen Roon app and restart it.
This is very repeatable, and does not happen on the android tablets that I have. (I can test with another Android phone later this week if that would help.)
Rob a OnePlus 9 pro user here.
I have it set to be excluded from battery/memory management and locked into memory as it is one of my most used apps.
I still get this a few times a month, but probably stable for 99.999% of my usage.
Take a look at the app options on your phone and see what is available, as it’s possible that it is being swapped out of memory or put into non active mode. You would be looking for battery optimisation options would be my guess
I suffer this problem with wy iPhone and iPad as well.