I've been having the same issue on my OP5 - Bluetooth and Inline Controls don't change track on the music player. Volume control works fine though.
Not sure if the issue popped up immediately after the 5.0.4 update, but it wasn't present earlier.
I've noticed however that bluetooth and inline controls work perfectly for the Google Play Music app. It is set as the default music app, and this can't be set to any other app like SoundCloud or Apple Music.
Anyone, please let us know if you've figured out what broke, or a work around for the time being.
Last edited: Mar 22, 2018