I've been messing around with the tall boxes with a friend and noticed a couple issues with them.

1. Interacting with the box while another player is inside the box will cause the player that interacted with it to freeze in place until they leave or die.

2. Breaking the box while someone is inside causes the person inside to remain invisible but be able to move around.

Suggestion: Make so items can't be used while you're in the box.

Another Suggestion: If a player right clicks a box while there is someone inside it. It will force them out of the box.