Hey Marijn,
You have to choose database, in the place of association,
into the datagrid,
As soon as you click database, you will see an option of ZroverlenerBulk_Zorgverlener on the very top of database selection table,
Select that association (from the database),
Let me know if you face any issues,
Hope it helps!!
You said you weren’t committing the list of Zorgverlener objects or the ZorgverlenerBulk object.
However, I see you are retrieving from the database in your screenshot. This will get a fresh instance of the object and you’ll lose the association between the two which wasn’t committed, which could explain why your list is empty.
I hope this helps.