Issue with Visibility of Custom “Select (User Role)” Field

I created a field that allows new members to give their “Position” (this will dictate their user role upon admin approval) when filling out the REGISTRATION form. This position field is tied to user roles I created. It works properly upon registration, but the issue manifests when I try to lock out the user from being able to change their “Position” (and thereby changing their user role) in the EDIT REGISTRATION form. I can make the field invisible in the EDIT REGISTRATION from by de-selecting “Enable Display On Edit Profile”, but that isn’t what I want. I want the user to see their “Position”, but not be able to change it. I was under the impression that the VISIBILITY drop down menu controlled this. However, whenever I select “User Locked” from the VISIBILITY drop down for this field, the field then becomes invisible in the REGISTRATION form, where it is most critical. It is my belief the behavior of this selection is not functioning properly. Can you help? Thanks.

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