Hello, no the pack a punch is not a contributor privilege, and will never be. About the issue I am not too sure what happen, are you playing on an online server? What are you trying to PaP?

I always play online. Pistols, rifles, SMG's, shotguns... nothing works. It's really weird; I seem to be the only person who can't do it.

Oh so it's working for other? If so that is super weird yeah... Maybe try unsubing/subbing again but this time check if the workshop is really getting an update in your steam downloads, maybe you paused a download so it's not updating the map correctly anymore.
Or the server you're playing on it not up to date either, so you can try making your own lobby

Thanks man, I'll give it a go.

Hey dude, just letting you know that I worked it out - I didn't realize that PaP is now a two-part process. A random dude on a different map set me straight when I told him my problem.

Oh yeah sorry actually I forgot to mention that you have to put your gun on the machine and then grab it :)

I feel like such a dumb-dumb. Something should have twigged when I realized it was the same for every map with a PaP and I was always the only one having a problem

Haha no worries :D