Auto Assign Role not Assigning the Role

I am running Backdrop version 1.15.x-dev  and have just installed Auto Assign Role Version 1.x-1.0.0 because I want new account users to be offered a couple of choices of Role, and then that can be automatically assigned to them when they register.

I have been a Drupal user for many years now, Versions 6,7 & 8. I am new to Backdrop, but hoping to be able to switch from Drupal 8 to Backdrop.

I have just enabled the 'User Choice' in the Configuration, and have selected a couple of Roles, Single Role, Selection Box, Required - Yes, with appropriate text in the User Role Description, with the rest as the default.

I then logged out, added a fictitious user to test it with a valid Email address.

After validation, the Role I have chosen is not activated although the user has the Authenticated Role.

In the Log I have this error after I log in as the administrator and look at the New User Account:

Notice: Undefined index: Host in views_handler_field_user_roles->pre_render() (line 36 of /home/francis/FG-Docs/public_html/wwoofbd.local/core/modules/user/views/views_handler_field_user_roles.inc).

The two Roles I have selected are Editor and Host

I have not found anything on Github about this.

Any ideas?