Almost all my music is downloaded from Beatport in stem.mp4 format for use on my DJ controller and plays fine in all my other music players but Poweramp will not play these files.
All my other formats like .wav and .aiff play perfectly fine in Poweramp.
When I load up a stem.mp4 in Poweramp it will play for 1-2 seconds then skip back to the beginning, play 1-2 seconds and continue this loop/skip.
A stem.mp4 should play exactly like a .mp4 as it contains a master track embedded in the file and the stock music player on my Galaxy S6 has no problems playing them but Poweramp won't