I have this exact same problem. It started when I upgraded my system from OS2 to OS3 (w C4-CA10 and replacing the touchpanels ). Never had this problem on OS2.
Actually, rereading, it may not be EXACTLY the same. It happens if I hit Pause in Spotity, but NOT if I End Session of the Spotify session within C4 (which is the workaround that does work, when I remember. I don't always Pause knowing that I'll be ending it (for the evening etc)),
TVC15, I'm a little confused as to your exact scenario (or perhaps multiple) you mention both pausing and swiping away, but also pausing and then ending the session.
For me it's longer than 5-10 minutes - it's more like a couple of hours after hitting Pause (first happened at some point in the middle of the night after we were all fast asleep).
My workaround has been to always end the C4 Spotify session, versus just hitting Pause on one of the Spotify devices. Which I usually remember, but not always. But rereading TVC15 sounds like he may be doing this? If so, I'm confused as to what exactly is happening - the last C4 Spotify session starts back up, and begins replaying on all the previously selected devices, if it the session was ended, and thus no active C4 listening sessions at all?
So very curious to see if a root cause is sorted out. The C2 to C3 may perhaps be a clue that it's something n the C4 side not on the Spotify side unpausing.
Seems like neither of these cases should happen:
1) A paused Spotify session magically unpauses and starts playing (my scenario, perhaps also one of TVC15's scenarios)
2) End ended Spotify session starts back up (sounds like this is what TVC15 also sees?)