Unsure if this has been reported or noticed, but when playing with my son on the 0.5 version in Multiplayer mode (private, steam friends only), we each can put things into chests, and then when you go back to it the items have all gone. We have both noticed it multiple times, and no its not one person taking the other persons stuff. We got a bunch of things to sell and put them in the chest of drawers, like magazines and cell phones and the likes, and came back to get them to to go the trader, and it was all gone, as well as a bunch of other random stuff. We hadnt been attacked or anything like that either, it was minutes later.

Also I really wish 2 or more people could look in a chest at the same time, as that is a real pain when trying to build a base etc, and you both want what is in a cabinet but you cant get in as the other player is in there.

Which leads me on to the next thing, that sometimes chests etc can say another player is using it, but they are way off on another island getting wood or whatever, but the chest is locked to their player. You have to wait for them to get back and get them to open and close the chest again and then its free to use normally. A real pain.

Noticed too when looting things, if you both go into the loot chest at the same time, you can get 2x the amount of stuff as you both can access it and see different contents...