Simply just activate one of your hacked items and everything will then function normally. When the race begins you will always start off with a default green shell, do NOT use it or else you will freeze. It means, that once you use your Item, nothing is left in your inventory (normal functions of picking up items from boxes occurs) because the Item Wheel Hack is turned off. In regards to deactivating the Item Wheel, this doesn't mean that whatever Item you have in inventory is cleared.
If you don't want this feature, remove the first 3 lines of the code (so the C2 line will now be the first line of the code). The code comes supplied with the ability to deactivate the Item Wheel completely and re-activate it later. Feel free to shorten the code if you don't need 13 hacked items. This code allows you to hack at will a selection of 13 desired items.