Some data is not pre populated in a form field - why?

Your software
My Mautic version is: 4.1.1
My PHP version is: 7.4.3
My Database type and version is: 10.3.34-MariaDB-0ubuntu0.20.04.1

Your problem
My problem is:

I have set a form in a mautic landing page to show data if known. This working just fine for most fields but not all. Why? I have compared the settings of the fields and all is the same, both in form config as well as custom filed config.

If I set the form to hide the field if data is known, they are hidden so the data presence is being recognised. But the form field stays empty

These errors are showing in the log: None that I can see

Steps I have tried to fix the problem: I have checked and compared settings with fields that are showing data correctly.

Check the JS console maybe there are some errors logged there that would hint about the issue?