"drush config-split:export" returns "Not enough arguments (missing: 'split')." I recently upgraded from Drupal 8 to Drupal 9. I've used drush config-split:export (drush csex) quite often. After the upgrade, it keeps throwing an error which is very vague.

Not enough arguments (missing: &quot;split&quot;)

No documentation says what the problem is, nor what that argument should be.
Any help would be much appreciated.
In order to use config-split:export with Drupal 9, make sure you go to admin/config/development/configuration/config-split. There you should see if you already have a split configuration and use machine name: drush config-split:export [machine_name]