Strange. I'm on experimental with three mods on (One map, Vanilla Content Expansion, and Combat Extended). Whenever I've been pressing C to enter the gunner cameras, simply toggles between first person and third.

I've also had this issue with one of the official Zeppelin Wars airship, so I think it may be a problem on my end.

Can you elaborate on why its not working because it works perfectly for me and anyone else who has used it

I've noticed here that the Heavy MG's camera doesn't seem to work. This is the same with some other creations you've made, think you can fix this?