An issue has been reported that contact records are unable to be saved under certain circumstances in the New UI.
When automated account creation is turned on, and a contact record has the Portal? field set to Yes or attempting to change it to a Yes, the record is unable to be saved if a parent account already exists in the database (PWA table) with a matching email address.
Programming has promptly identified and fixed this issue, and it will be released with today's 7/14/2017 update.
This issue has been fixed with our 7/14/2017 update.