Hi all,
I've signed up especially because of this thread. Sorry to say I've had the same problem happening several times, always on a flight, with the phone in airplane mode, most recently twice in a week and a half, on the way out, and on the way back - very frustrating. Running Poweramp 2.0.10-build 588-play, with version 2-build-26 of the unlocker, on a Samsung S5 with Android 6.0.1.
I like Poweramp for the most, and music, with my Bose noise-cancellation headphones, is a life saver on a flight (or train ride, actually), but I'm actually getting to the point of looking for an alternative. Having to realise that it's not working - again - due to not being able to check the licence, and having to switch to the stock player - again - is not what I got this for. I realise it wasn't much money, but still...
Cheers,
Olaf