Unfortunately the Secondary Usergroup field is missing the 'Can User Edit This Field' option. This option is available for all fields, except for the Secondary Usergroup field.

It is required to have this option available for the Secondary Usergroups since it is the only way to make it possible that a member requests access to a private subforum and Forum Administrator can grant or withdraw access to a secondary usergroup without having WordPress Administrator role).

See screenshots.

Kind regards,

Maaike