Check if Groove is allowed to run in background.
To do this open Settings app. In the search bar, type
background apps and tap on the first result of the same name. Or go to Privacy > Background apps.
Here you'll see a list of apps each having an on/off toggle.
Scroll down to Groove Music and check if the toggle is set to
On. If no, turn it on. If yes, turn it off and on again.
Now, go to System > Battery > click the blue link titled
Battery usage by app
Wait for the list of apps to appear. Scroll down to Groove Music (If you cannot find it in the list then set
Time to
1 Week at the top of the page).
Tap on Groove Music and select the first radio option titled
Always allowed in background.
Done. Now see if you can reproduce the problem.
If yes then try restarting your phone and as a last resort, hard reset your phone.
Hope this helps