As we know minisign can plant at any place if that point has no right-click actions, and some people can easily set these signs on chests. When playing the game with Keyboard/Mouse, and no shovels in hand, players first target chest instead of minisign, which means they can open chests, not inspecting signs.
However if one plays with Controller, due to load/unload an area, he will sometimes inspect the sign instead of opening the chest, making him unable to store items or restore from the chest. And this is not what I expect.
I met this bug so frequantly on my dedicated server, with caves ( And I don't know if it contributes to this bug), and my controller is Xbox Elite. Anyway, hope you can fix this soon.
Here's a pic, and you'll see what I said.
1. Connect to your controller first. 2. Try to set a minisign on a chest. 3. Leave this area and come back later. Repeat this if you still can open the chest. 4. If #3 didn't reproduce, try to relaod the game. And you might see it next time.