What? What do you mean, why? Because of this thread, of course! This is a problem of your own making. You need to have xmp files so you can easily transfer your edits.
Changing that setting back to how it's supposed to be will prevent this problem in the future, but I'm afraid I don't know how to fix the existing problem, sorry. There must be a way to export the xmp files from the database, but I won't be able to test it until tomorrow.