by Ken Task.
Getting closer ... first ... ad_hoc cron, if I re-call, is an old cron process. Don't re-call in which version of Moodle but there is now a recycle-bin for a course. Deleting module in a course would trigger the re-cyclebin for the course which uses backup to keep the resource/module in a position to be restored.
Best guess!
'spirit of sharing', Ken