Upload task always report "No candidate objects found".

Execute scheduled task: Object file system upload task (tool_objectfs\task\push_objects_to_storage) ... started 17:23:06. Current memory use 36.6MB. No candidate objects found. ... used 1 dbqueries ... used 0.18827605247498 seconds Scheduled task complete: Object file system upload task (tool_objectfs\task\push_objects_to_storage)

On moodle 3.8.3.

Any idea on what could be wrong?