Perhaps it was due to some system-wide cleanup activities, but I encountered this when trying to submit the mixed game 2 or 3 minutes ago and thought I'd bring it to the attention of the admins:

Uh oh!

The question set that you just played has expired. Either the server restarted while you were playing, or you played just as the tournament was closing.

You seem to have hit the midnight maintenance - all kinds of strange things can happen between 11:50pm FT time and 12:10am FT time. I try not to play any active games in that time frame, just to avoid the potential issues.

With the timing you mention, you likely started your play right before midnight and ended after it. I would bet this has caused some unusual timing exception upon which the system rather discarded your game than trying to score it.