It sounds similar to this other issue (simplenews-7.x) where someone inadvertently used the 6.x actions definition: http://drupal.org/node/809276

PDOException: SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'type' cannot be null: INSERT INTO {actions} (aid, type, callback, parameters, label) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1, :db_insert_placeholder_2, :db_insert_placeholder_3, :db_insert_placeholder_4); Array ( [:db_insert_placeholder_0] => maestro_launch_workflow [:db_insert_placeholder_1] => [:db_insert_placeholder_2] => maestro_launch_workflow [:db_insert_placeholder_3] => [:db_insert_placeholder_4] => Launch a Maestro Workflow ) in actions_synchronize() (line 293 of /var/aegir/platforms/globalverify-7.x-2.0-alpha1/includes/actions.inc).