UBB.threads PHP Forum Software Community Forums UBB.threads 7 Version 7 Support Moving member between groups - 'users' not available

I just did the upgrade from 7.1 to 7.3.1
I have this routine that every month I upgrade the new members that have post from "new User" to "Users".
I try to do that then I realized that "users" group is not available on the list to ADD on the "Change Groups" (membersaction.php).
All other groups are there but "Users".

Am I missing something?

THank you