Snapshot Article 20w20a uses the wrong name for the advancement type.

ADVANCEMENTS

ITEM_USED_ON_BLOCK TRIGGER TYPE

Properties:

• item matches the thrown item which was picked up
• entity matches the entity which picked up the item

 

This should say

ADVANCEMENTS

thrown_item_picked_up_by_entity TRIGGER TYPE

Properties:

• item matches the thrown item which was picked up
• entity matches the entity which picked up the item