That’s more so related to interactive JS on the form not working. That’s an issue I’ve run into in the past and actually that exact post helped in that case, but this is a different issue.
It seems like the problem here is related to the actual rendering of the form elements. Unless maybe some JS is removing the attributes after output, but that seems fairly unlikely since all of the other fields render and save correctly.
I get the impression I’m experiencing the same issue that’s noted as being fixed in the 5.4.2 update, just applied to an AJAX loaded form.
