I used Poweramp v3 816-play with Nexus 6, Android 7.1.1.
If I disabled lock screen in Android option then after lock/unlock I observed Poweramp menu (I expected something like to lock screen in old UI version).
If I enabled lock screen in Android menu and pressed lock/unlock then I also see usual Poweramp menu but then after few seconds it switched to default android lock screen.
Pleasee see attached video.
Can you attach scren shot how Lock screen should look in new Poweramp UI?
20190102_085818.mp4