I and a friend noticed ranger special arrows not appearing back. The game seems to know it should be back because you can grab the other arrow to update the bugged one to show up. It seems to happen frequently.
Its an annoying bug to keep on top of as unless you play the same class a lot or are actively thinking/knowing it should be back then you can miss it even happening. It started appearing after the fix for arrows to show up. It was actually better before that patch although not perfect still in a different way.