If I had to guess, probably technical issues with them either not having a proper PAP model or it won't just convert over to the standard gun for PAP.

Latest version seems to be a bit bugged: Der Riese stopped spawning zombies during round 12, Shi no Numa zombies one shot if you don't have jug, and the mystery box seems to be a mess (Der Riese doesn't give anything, Shi no Numa keeps dropping teddies on the first roll, etc.)
 
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