Hi there.

I think, it's supposed to drop one of the courtyard trinkets.
The "helping hand" event was active, so my party was a little higher level than usual in that area.

Shoud anyone wonder, I don't need the gold and I'm in no dire need of the heirlooms, therefore I prioritised keeping as many supplies in hand as possible.

Cheers and best regards from Zoppy.

The problem might have been, that I used a key on the chest. A bit weird to have a lesser reward from using a key on a chest.