I was looking for the metakeys your talking about both in postmeta and termmeta but I can’t find it.
I’ve also tried @nicholasarehart suggest but I can’t get it working.
If I change my image field name from image_name to _thumbnail_id I can do the trick to use my old image_name image as post-thumbnail, but I losted all the old images, so I’m trying to fix it changing those metakeys in the database.
Thanks for this solution, but if I’ve got an existing image field and I replace the name field from my field group, all my old images go away.
How can I keep them if I change the field name?