I assumed that you have cleared the cache and refreshed. If that did not solve the problem look at the bottom of the screen (you have to do this for both the bank and the inventory) there are two numbers separated by a slash. There are the number of used slots and the total number of available slots. If the number of used slots plus the number of empty slots that you have is greater that the total number of available slots then you have some items hiding behind other ones.

If this is the case you need to move the visible items one at a time to an empty slot until the hidden item shows in the slot that was vacated by the move. You need to continue doing this until the numbers add up correctly. Do not forger to move the item that was revealed, because there could be another hiding behind that one.