Since by definition the two ID fields carry the same value, why not use License 5::ID and ::email, and make it a conditional value list, using related records, starting from License?
(And you should really use better TO names …)
I have conditional values starting from License. Still have the same problem of no values defined in the popup.
Ah, I'd added the relevant field after making the records, so of course, there was not entry, therefore no value to grab.