im also using the WSA / Poweramp. i had this issue before but i found away around to select native windows folder to scan. wich was the native music folder of the windows. it works flawless.
check the scren shots,
1. Open WSA
2. Advance Setting
3. Experimental Features : Turn On - Share User Folder
4. Select user folder (PC)
5. Go Back to WSA System : Files : Pixel 5 : Windows : (Select the folder where your music Stored)