How to show popup when DB data missing?

I’m a little perplexed as to why I can’t figure this out, I have a feeling it’s very simple!?

My users can create an invoice. To add a customer to their invoice they click on “Customer” text which opens their “my-customers” group and they can select from their list of saved customers (screenshot below)

Screenshot 2021-10-14 095930

I’ve created a custom state called “emailPresent” and planned on adding a constraint to the “Customer” text, something to say if the Customers Email is empty then show popup. But, the customer email is always empty when you first land on the above page so that won’t work. Any ideas guys?

I have figured out a way to achieve this.

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Then the next step in the workflow will show the popup with the same Only when restriction. Together these two steps work fine.