de0u
Ok. Thks for your response.
So I have four profiles - the default admin profile and three others I have set up.
This usually only happens when I am listening to the BBC Sounds app in my regular profile although I usually have Signal open constantly in that profile too. I can't say I've seen this at other times say when my phone has been sat idle in the house for hours.
The music stream will stop playing and when I check the phone it has the notifications I stated previously:
In the current profile I get:
GrapheneOS.Other users.now (this is the category heading for the notifications)
"Notification from GmsCompat for profile B" (this is the notification - one for each of the other user profiles)
"Notification from GmsCompat for profile C"
GmsCompat (this is the category heading for the notification in the current profile)
"Sandboxed Google Play is running" (this is the notification for current profile)
Sometimes also included is the notification...
"Apps are up to date"
I then try to swap profiles to clear notifications and the sytem will take a long time to switch and sometimes reboot fully and restart me in the Admin profile.
I hope this is a bit clearer.