Bruce,
I am not sure what causes the lock, perhaps it get’s set when the Job header schedule lock is enabled in Job Entry?
While I’m not sure this will help, here is a post from another topic the might be beneficial regarding various conversion programs I have used to clear up odd scheduling issues. However I strongly recommend that you work with Epicor Support on this and not run these conversion programs in your production environment without adequate testing in your Test environment.:
-Rick
www.getaligned.solutions