Is there another field also being saved on the same post with the same name?
I just had a similar problem – I have a group of flexible fields called “image_blocks” that I was cloning into a field called “image_blocks” in another group. I didn’t realize that every time I saved the post, my flexible fields were being overwritten by the parent Clone field.
I would recommend naming the Clone field something like url_clone to avoid collisions, if that’s your problem. It would be great if the plugin could automatically detect confusion like that.
