Yes, I've been informed of the furniture disappearing, unfortunately the script I'm using appears to happen on certain computers/devices and there's currently no fix around this.
You will need a chest to collect your loot from the loot box itself.
Fortunately, I added the Loot Box to be purchasable from the furniture store at a low cost and other essential furnitures in case anything like this happens in the future. Hope this helps a little in resolving your disappearing furniture.