nickname field does not update

Hi,
I have put a “nickname” field in a registration form and then in the profile form on my website, but for some reason, the users cannot edit the “nickname” field.

When you click on the update button it does not send any API requests. You can see it here:
https://imgur.com/a/VSBNl2F

And also after you click on it the button “grays out” and you cannot click on it again. A small “denied” sign is showing next to the mouse pointer. You can see the screenshot here:
https://imgur.com/a/s5atSE2

The cancel button is working fine, but the update does not.

P.S. I have allowed the users to update their profiles.

Please advise what could be the reason.