Is the AK Server side? if so, that might be why its not showing up there.
I expect that to be the issue because you never mentioned about having the Weapon yourself, just "(the ammo for our custom AKs which was working fine before)" Which i may think means server side. If its not your server, contact the owner and have him paste the Custom AK to the forums or somthing :s
Sorry if I did not help.
I was able to arm maps using the AK and view them in single player before, and like I said this isn't an issue with only the AK. Most vanilla weapons/ammo aren't appearing at all for some reason.