I've seen similar thread, but it's Mac.
I'm on Windows 10 PC, Spotify v184.108.40.206.gb8a7150f.
My Bluetooth headset's Play/Pause button doesn't work with Spotify even when on-focus. Prev/Next button works fine.
Everything works well with Windows Media Player.
Tried 2 different Bluetooth headset, same issue.
Solved! Go to Solution.
We have a fix coming up in 1.0.35 that I think will resolve this issue. 1.0.35 is expected to go out in 2-3 weeks.
Sorry for the inconvenience!
I just updated to Spotify v220.127.116.11.g1cba1920 and now this seems fixed!
But there seems to have been some issue with the automatic update of Spotify. I was stuck on v1.0.34, where the "About Spotify" window did not show any update available. Then I downloaded and reinstalled from spotify.com. Then v1.0.34 was installed again, but now it found an update when checking in the "About Spotify" window... That automatic update brought me to v1.0.36 and problem solved!