I may have opened my library in 3.4, but if I did, I did it in a separate portable install. I did not overwrite the main (installer) version of 3.3 that I use to sync with 3.4 at any time.
It synched the PLA files. I couldn't figure out why PowerAmp wasn't picking up my playlist changes yesterday. Today, I looked in the playlist folder and saw PLA files from today and the last M3U8 from 4/13. That's when I opened MB and saw that the playlist type was changed to PLA. I thought I may have done it by mistake without remembering going into the settings, but it was the same in all my devices, even devices I no longer have and haven't looked at in MB for some time.
Might it have been the debug version?
A smile is happiness you'll find right under your nose.