Can't change Primary Email to email that is already added under Emails.

I'm using the gitlab.com hosted site.

I've added a second email in the Profile ==> Emails area.

When I try to change my primary email on the main Profile page I always get a "Failed to update profile" message.

I've tried just clicking the "Save changes" button, I've tried pressing the enter key, and I've logged out and back in again and done both the "Save changes" and enter key again. All with no success.

From discourse thread - https://forum.gitlab.com/t/profile-settings-emails/312