I have Poweramp 2.0.10 build-588 (the latest version of Poweramp 2 available on Google Play) installed on my Moto G 2015 running stock Marshmallow (I believe fully updated as well). My bluetooth headset is an Audio Technica AT-PHA50BT (listed on their site as a bluetooth amp) with apt-x support, with the usual three-button playback setup (previous, play/pause, next). After my bluetooth headset is connected to my phone, music playback is ok, and of course I can control playback on my phone, but the bluetooth buttons are completely unresponsive — even play/pause doesn't work! Yet all three buttons work when I play music and video on Spotify and VLC. As sort of a last resort, I've tried resetting Poweramp entirely (going to Android system preferences -> apps and clearing the app's storage), but to no avail.
I also have an Asus Zenwatch 2 (an Android Wear smartwatch) connected to my phone at all times, and music control (play/pause, previous, next, volume up/down) from the watch doesn't work as well, so I'm guessing it's an issue with the way Poweramp is communicating with Android's bluetooth A2DP service? I've tried resetting just about everything (headset, watch, Poweramp, everything short of a hard reset of the phone itself, although I don't see why I'd need to do that since I got it fresh just a few days ago), and playback controls still don't work at all. Please help.
EDIT: I might add that my previous phone was a Sony Xperia Z3 Compact, which I had for about a year and a half, and bluetooth playback control used to work properly but suddenly just stopped working about three months ago, I have no idea why, but I never tried troubleshooting the problem. Also, I acquired my headset before I bought my smartwatch, and these two had no issue regarding playback control for about half a year, but suddenly bluetooth playback control both stopped working for no apparent reason (music still played ok through the headset, it's just that I have to pull out my phone to control anything)