Am from California. It would be mega, extra special beaucoup illegal here. If you are not free to leave, you are working according to state law. PERIOD. That means two things in this case. First, every single such lunch is wage theft. Second, your store is violating meal compliance, because California law requires an unpaid meal break, and as far as the law is concerned, you didn't get one, because you were working unpaid instead. I don't imagine our labor board would be impressed.All stores in my district enforce the policy. The reasoning is that the alarm must remained armed during certain hours. If it's taken down during restricted times, alarm exceptions pop up. It's actually a store metric.
I still don't understand how the policy can be legally enforced though. Some states are very worker friendly and I'm surprised would allow it.
If you're not being paid, you must be free to leave.