I was in the middle of my third battle on a delve for the all seeing eye faction on Xbox One and the game restarted. When the game started back up, it went to the reward screen as if I had ran away. So I lost the delve.
Later on I tried to upgrade the hoard level in the same delve and it froze up with server error in the middle of upgrading, so I lost my treasure and gold. I did retry many times, but it never came back.
I have a video clip and a screenshot from both errors. I can email them if you need to see them.