Unable to deliver items to customNPCs

[raxiam]

Description:
Unable to deliver items to npcs created with customNPCs.

Reproduction Steps:
Create an itemDeliveryObjective inside a staged quest, give it minecraft:stone or any other minecraft block, and have the UUID reference a customNPC created npc. Then try to deliver the stone to complete the objective.

Try again, but with a villager created with the following command: /summon villager ~ ~ ~ {NoAI:1,Offers:{}} (this works)

Expected Behavior:
The npc is supposed to accept the item and complete the objective.

Observed Behavior:
Nothing. The item remains in the inventory and the objective is still unfulfilled.