Be careful blocking your door you could experience issues, like a quick sell.
The game will usually quick-sell all of your inventory if you block the door to your store. When you block the door, you may not see the customers coming in, but the system will still recognize them walking in and buying your items. When you open your door again, the consumption that took place while your door was blocked catches up, which is why it looks like you instantly lost all of your items.
If you want to avoid the quick-sell, don't block your door.