I dunno if this happens all the time but it does definitely happen from time to time.
Just before on bridge defense before the game started I ran around as Arty and dropped 4 packs on the ground and I was the only person on my team capable of dropping packs.
Just before the actual game started I changed to Aimee, and after we all spawned my ammo packs were still on the ground and we were able to pick them up.
They should have disappeared shouldn’t they? Since I changed mercs any way.
I’ve seen Sparks do this as well with her packs as well.