Alexb1096 I made a quick simple multiplayer map and used some weapons from the ww2wp pack.
Now note I didn't have someone to play against, just myself in the test map, but weapons seemed fine?
They picked up & switched as intended. I didn't see any problems like you were having

Now this was in a "multiplayer" correct, not single player?
The one thing you could do is to make a very simple (small) map, using stock items only, and upload it here (just the .fpm file)
That way someone could text out your map and see if the problem occurs?
My games never have bugs. They just develop random features..
Lots and lots of random features...