Since update 18, the bag inventory is very slow. Trying to move items (other than shift-click) is often refusing to drop items in both the bag and player inventory temporarily, as if the server/client couldn't keep up.

In addition the 6th slot (from top-left) is not allowing me to pick up an item placed there. The item type does not matter, I had different items locked in the same slot so far. Very rarely I can for some reason pick up the item, but then the next one that goes into this slot is locked.

this happens because in that case, slot 6 on the hot bar is locked so you don't pick up the backpack as its in use. the bug is that slot 6 on the backpack inventory is also locked. Will fix.

Fixed via 607d45f