I have created DFF and I'm using the default type as SQL but data are not auto-populate in the UI

I created the Value Set using the default validation type as SQL, but the data is not auto-populating in the UI. When I check the backend, the data is present, but it does not appear in the UI.
I also tested the Value Set separately, and the date is appearing in the field. However, when I select “Note to File” or “1st Warning”, the system shows an error. If I select any other value, I am able to submit successfully.
I am using the below query in the Value Set:
elect d.expiry_date
From (SELECT TO_CHAR(TO_DATE('01/01/1951','DD/MM/YYYY') + (LEVEL-1), 'DD/MM/YYYY') AS expiry_date FROM dual CONNECT BY LEVEL <= 1000000) d