Did not the chance to reproduce it but thats what I did:
what I've done:
- crafted courier bag with full inventory and ak74u in hand
- courier bag did not appear (different bug)
- switched to AK74u after crafting was complete.
- switched to fireaxe
- climbed over a fence
- ak7u was not VISIBLE in the invetory anymore
- Could not equip any other weapon. (slot full)
- a relog let the made the weapon visible again.