I don't know for sure when Prokyon DB access broke, but here is a simple patch for 0.8.13 to fix Prokyon.
Not sure about this. Did you discover P3 access broken only on a converted Ampache database?
The P3 database is the origial one that I used before switching to Ampache.
I have a script to create an Ampache database from a P3 database, but not the other way around.