This Dropdown isn't valid is just a condition on the dropdown. I can see that you’re using the Standard Dropdown style—If you head to the Styles tab of the editor and search for the Standard Dropdown, you’ll see that condition is there.
What you see is not your issue; it’s a data issue.
Are you adding the records to your live database but previewing the development version? They are two different databases, which could explain the empty list you’re seeing…
Hi there, @LocoMoco… the configuration you are using for your dropdown should work, and since it isn’t, privacy rules come to mind. Do you have any rules in place on the Equipment Master data type that could be getting in the way of the dropdown’s search?
You were totally right! Thank you so much for the suggestion. Somehow, I had inadvertently added a privacy rule for the table. Once the rule was removed, the dropdown list worked.