I'm playing on co-op and when you access inventory and right click an item it lists a bunch of things you can do with that item. The keybinds are set up in settings. It isn't like removing the keybind or not saving it. But those keybinds for drop/inspect/ etc just aren't doing anything and aren't even listed in the brackets of the drop down menu (text in down will read Repair [ ] or Drop [ ] like nothing is bound).