One of our players has, while playing with water, activated a nasty A10.1 bug: invisible waterflow.
This means that when water is placed above groundlevel against a wall, it's radius ( a 2x2 from the place where water is placed) will reach through the wall like it isn't there, dus despawning all playeritems (like chests) within that area.
As of yet, I HAVE NOT BEEN ABLE TO FIX THIS! It is most likely impossible to retrieve any times that were in the disappeared chests/crates/safe's/etc.
Are you affected by this bug? Please contact me, and I will see what I can do for you.