Hi,
We changed our timezone under Settings > System > Internationalization.
After changing the timezone, all our tickets are now gone. Reverting the timezone change doesn't fix the problem. We are so confused why all our tickets would disappear simply by changing the timezone.
UPDATE: Our tickets are still available via ticket URL. But they are hidden on all our boards. All we did is change the time zone. The filter for the board does not show us anything that should result in tickets not appearing.

Any help would be appreciated.