I have the same issue on S21 Ultra with Android 11.
It finds 0 tracks and each time I open music folders in settings - folders are unchecked. I check them back, "select folders" button and nothing changes.
Performed app's data clean-up from system settings and configuring once again - same issue.
BTW, other media player (FiiO Music) works well with same folder and same permissions granted.
This FAQ entry does not help: https://forum.powerampapp.com/kb/en_us/faq/music-folders-selection-doesnt-work-on-android-1011-and-other-file-access-issues-r36/
I am ready to do some adb logging and other possible troubleshooting to help with it.