Anyone else having this issue? It seems to have only started over the last few weeks. I can't figure out if it's a Spotify change, iOS change, or some setting that may have been accidentally changed.
I have noticed that trying to use the Remote app to change my TV volume requires me to quit the Remote app and re-open it to then have it change the volume.
My guess is an iOS bug. I know quitting Spotify would stop the music, not a solution for you. Sharing my experience however.