I get the same problem with headgear, however its only ever headgear. Basically you go to replace the item on your head with one on the ground and it doesn't swap. Then you cannot change headgear ever again. If you drop the headgear your wearing to the ground you lose it but you still cannot pick up any other headgear or the one you dropped. Logging out and reloading fixes the issue and whatever you dropped or swapped too will be on your head. So it appears its a sort of visual problem that then effects your ability to replace or pickup other items.

I ask only because when i played previously (offline and the stress test) the bar was visible, but was clearly not visible this time. I had to press the toggle to enable it. Maybe if what i remember is right it should be showing though and that is a bug.

Did you try pressing the ` key. (its above TAB)