Account Update bug by backend..help

I tried to change password of a user by administrator back end, and when I click on save butto an error message appear on the top:

Select a "Sex" from the list.

there arent Sex fields, and password dont update. After that I tried to do the same thing into flynax (website) demo back end, and appear the same error message. Maybe is a bug or I mistake something? can someone help me to understand how to update user password by back end^?Attachment 2137

Attachment 2137