I've attempted both options:
creating a text variable, assigning the email field's value to it, and then updating the text field with the text variable; and
updating the text field directly with the email field.
In both cases, the Flow does not recognize the value of the email field, even though it's not blank on the related record. Please note that updates work correctly with other field types like Email to Email and Text to Text, but not Text to Email.
