I appear to have found a bug with the item detection system for inventories, when pressing 'q' over an item in the inventory, testfor (and possibly scoreboard NBT matches) are not updated, as shown in the attached file.

Steps to reproduce:

Setup a repeating command block and enter this command with a comparator obtaining an output:

testfor @p {Inventory:[

]}

Then give yourself some Elytra:

/give @p elytra

Now, with the comparator powered, throw the item by opening your inventory and pressing 'q' while hovering over the Elytra, you will notice that the comparator stays powered although it is unpowered if you throw the Elytra any other way.

Charlie