Hi,
sorry for late reply.
Update: Seems the issue was a space before a user profile name in the database.
Yes, Joomla does not allow usernames like this.
If I try to add a space before the username then I get message "Profile could not be saved: Please enter a valid username. No space at beginning or end, at least 2 characters, must not have the following characters: \ " ' % ; ( ) & and be less than 150 characters long."
I can however edit a profile created in Joomla. It appears the issue is with profiles created through Easy Profile
Have you created these profiles from Easy Profile? Easy Profile extends Joomla user management, so the registration form is the same of Joomla with some improvements.