I finished an expedition and ported back to town. I then had to answer the door and left my character in town. When I came back I had been kicked to the Main Menu screen. I logged back in and clicked on the Expedition table, but no reward came. Thinking I had perhaps already done that before I answered the doorbell, I checked my town building window and found zero progress on my active projects.

It appears that after I was afk kicked, I lost my reward.