Item bug problems

During games, there are these weird looking boxes that are frozen on the screen after killing a lot of minions. No items actually drop from them until you actually fight the opponent, and that actually starts crippling my team late game. I have no idea what item(s) I got and I can't access any until I leave my screen to fight someone else or go to champ selection. This needs to be fixed asap because it makes the game horribly hard to win.