Cannot prevent humans from picking up items

[Catlord-3]

So basically I have tried to make it where the humans in this mod cannot pick up items, by using the nbt tag. When i spawned them in they would still pick up items, even though i did not want them to and i made sure i was using the correct tag, it still wouldn't work. Can you please resolve this as soon as possible. The only way to stop this was to turn off mobgriefing, which i want on, and it should be possible to make them not pick up items using nbt.