Customers stopped coming

Hobbies and business pack. 

I started a pottery studio lot. My sims live upstairs and the classes ans studio are downstairs, but sims randomly stopped coming. 

I have it all nicely decorated, kiosk and till, both accessible, good reviews and two stars and two employees. 

When i open the store the two employees turn up, all the employed sims begin holding classes and doing thier daily duties. But no customers arrive, sims walk past, the maid arrives to do her job but nothing. The doors are all unlocked, curb side appeal is there and the bottom floor is set to public. 

Please help, why has it randomly stopped?