Ah sorry, I see why that doesn’t work. I’ll get that fixed for the next release.
As a workaround you could run some SQL and then run the task again:
UPDATE `media` SET `orientation` = NULL WHERE `type` IN ('image', 'video');
If you only wanted to do image or video you could adjust the IN clause accordingly, and if you wanted to test a few first you could add LIMIT 1 to the end of the update.
Thanks!