So I recently bought the gladiator pack on the market, unlocked it into my inventory, activated it, but I didn't get the achievement. Is this a bug?

HELP ME PLEASE!

usually u need to wait for some time to get the achievement, not meaning that u won't get it
so just wait it out

That is the way for all of them other then belts i believe.

Ok. I'll keep that in mind next time. Thanks!