When a new user creates a site (paid or free) the password sent in the welcome email doesn't work. The user must do a password reset to get a working password.
This is similar to this ticket:
https://premium.wpmudev.org/forums/topic/wordpress-pro-sites-newly-created-users-wrong-password
The difference is that I do not have the Manual Payment gateway enabled. Free sites are affected, so payment gateways are not involved.
Support access is enabled.