Amazon has had to hold fire on its plans to open its store of the future to the public in early 2017 because, well, it doesn’t yet work properly.

According to the Wall Street Journal, the cashierless grab-and-go Amazon Go store in Seattle – which is currently open to Amazon employees in Beta – is facing some teething problems. These problems relate, in particular, to the technology that tracks customers in the store not being able to keep up with more than 20 people at a time, and it having difficulties tracking items that have been moved from their original spots.

The checkout-free system is also experiencing problems in tracking people in store – unless they move very slowly, presenting a bit of a problem if you’re in a rush, and the fact that efficiency is the entire reason for the store.

It had previously been reported that the store also required human help when it wasn’t quite sure of what somebody had picked up in store.

In its current form, the Amazon Go store sounds like it would be really easy to steal a heap of shopping from and they’d be none the wiser. Amazon has a lot of work to do before the store realistically gets off the ground. Here’s a video what Amazon hopes the store to be like.