I have another version of the issue described in the OP. I have a consent clause to which new users have must agree (tick the box) at sign-up. The custom user field is configured so that it cannot be edited afterwards, but since it is nevertheless displayed on the user preferences, users can still attempt to change it. But when they try to save the preferences they are told “You have not completed all the user fields”, which is confusing for several reasons:
- they don’t know what “user fields” are
- there is no indication as to which user field is missing
- since it is a tick box, there is nothing to “fill in”
- the real problem is not that they have not filled in everything, but that they have withdrawn their consent by unticking the check-box
I will work-around this by hiding that user field via CSS, but the UX regarding user fields can definitely be improved.