This app works fine, thanks clever_man.
A little bug I found: The pause button on notification it's bug, when I pause in the button, the pause symbol not change to play symbol, but the function of play/pause works fine. I use Poweramp v. 2.0.10-build-588-play with your Poweramp Notification Helper 1.40 and Android 8.1.0 with Xiaomi Mi A1.
I attach two screenshots with the problem.