Change 1000+ of WordPress Featured Images in 5 Minutes! › Forums › Questions and Answers › Image not removed from post › Reply To: Image not removed from post
I am not informed about any mess with LightBox. I highly recommend to make a backup at least of the database before applying QFIP. Then try with the help of the filters a change at one or two posts and see the result. If the result should not be ok you can make a rollback with the backup.
To #2: You can overwrite existing featured images to fix them. Does this answer help you?