After cloning double chest can't open inventory or chests

I've been trying to clone a double chest, but it's giving me some problems.

1. Instead of being cloned as one long chest, it clones as 2 regular chests (attached)
2. More importantly, after cloning, I can't open the chest or my inventory. I can still move and destroy stuff and open and close doors though.
3. Trying to save and exit game gets stuck at saving screen (attached), and the only way to exit the game is actually to click the x at top right.

Steps:

1. Create a long chest.
2. Fill it with things.
3. Clone the long chest.

Update 2: It seems that there are no problems when cloning an empty long chest, but obviously there's no point in cloning a chest if there are nothing in it.