I got a problem on Android 8.1.0: the notification shows the wrong album cover.
Reproducing the problem:
Start music, cover is displayed correctly
Change track, either from notification or Poweramp app, the cover does not change
Change track again, the album cover changes, but to the previously played track's.
So this happens: track1 cover1 → track2 cover1 → track3 cover2 → track4 cover3 → etc
See attached video: