Just traded a few items to Dispenser 20 and they went into the bot limbo again.
El Jefe, Diamond Minigun, Diamond Flamethrower, Carbonado Sniper, and a Stealth Steeler. I can see them in the inventory, just not available in the store inventory.
I tested it again with 5 crate 44's and it did the same thing.
It happens here and there for some reason, though you always seem to find them. Might have to look into why it's doing that.