Issue: User -> add user doesn't work. Unable to enter a password for any new user created after initial user and first boot, and so unable to create usable user login.

Tested in Budgie and Gnome variants.

Steps to reproduce:
Go to the user click add user section of Settings. Unlock. Add User. Enter new user name.
Allow user to set a password when they next login: Next time you try to login, you have to type in a password, but there is not set password, and there is not option to set a new one.
Set a password now: Does not work. The Add button is still grayed out.

Expected behavior:
Should be allowed to either add user after setting password, or prompt to set password next time you try to login.

This is related to this bug: https://dev.solus-project.com/T5020
However, it is different, as that refers to adding privilege to user, and this bug states that adding a user cannot be done.