Hi,
I re-checked the code, but based on the bp database it should be the correct solution, so I honestly don’t know what exactly is wrong here. The ‘item_id’ column should be the foreign key to the group related to the activity, as far as I was able to tell.
Please let me know if you know anything about this, and I will try to update the code accordingly. Unfortunately I cannot guarantee customizations to work in all cases.