Can´t add new contributor

I have an multi Site.
on the Main site i can´t add an contributor. On the “under” Sites it works fine.

9.09.2020 18:40:23 .de [client 85.190.89.0] PHP Fatal error: Uncaught Error: Call to a member function update_attributes() on null in /mnt/web201/e3/37/54250737/htdocs/WordPress_02/wp-content/plugins/podlove-podcasting-plugin-for-wordpress/lib/modules/contributors/settings/generic_entity_settings.php:93
19.09.2020 18:40:23 .de [client 85.190.89.0] Stack trace:
19.09.2020 18:40:23 .de [client 85.190.89.0] #0 /mnt/web201/e3/37/54250737/htdocs/WordPress_02/wp-content/plugins/podlove-podcasting-plugin-for-wordpress/lib/modules/contributors/settings/generic_entity_settings.php(67): Podlove\Modules\Contributors\Settings\GenericEntitySettings->save()
19.09.2020 18:40:23 .de [client 85.190.89.0] #1 /mnt/web201/e3/37/54250737/htdocs/WordPress_02/wp-includes/class-wp-hook.php(287): Podlove\Modules\Contributors\Settings\GenericEntitySettings->process_form()
19.09.2020 18:40:23 .de [client 85.190.89.0] #2 /mnt/web201/e3/37/54250737/htdocs/WordPress_02/wp-includes/class-wp-hook.php(311): WP_Hook->apply_filters()
19.09.2020 18:40:23 .de [client 85.190.89.0] #3 /mnt/web201/e3/37/54250737/htdocs/WordPress_02/wp-includes/plugin.php(478): WP_Hook->do_action()
19.09.2020 18:40:23 .de [client 85.190.89.0] #4 /mnt/web201/e3/37/54250737/htdocs/WordPress_02/wp-admin/admin.php(175): do_action()
19.09.2020 18:40:23 .de [client 85.190.89.0] #5 {main}
19.09.2020 18:40:23 .de [client 85.190.89.0] thrown in /mnt/web201/e3/37/54250737/htdocs/WordPress_02/wp-content/plugins/podlove-podcasting-plugin-for-wordpress/lib/modules/contributors/settings/generic_entity_settings.php on line 93

Created a bug report: https://github.com/podlove/podlove-publisher/issues/1148