Original file name is located under "example" but missing from everywhere else.

I recently moved my photos and catalog to a new external hard drive. During the process, my catalog photos were renamed, and are now no longer associated with the original image files.

Normally you could go Library->Rename-> and choose the original filename, but because the photos are considered "missing" I can't select the rename option. I can't find them all individually as I have 13k+ photos, but the original name for each file is showing up in Lightroom in the library tab, under the metadata dropdown, when I select "batch rename". If I do this, a dialog box pops up, and in this dialog box, next to "example" is the original file name.

That means that Lightroom knows what the original file name is. How does this information get in, and how can I use it to find the missing files? Adobe support's response was to find all 13,000 photos by hand or reimport and lose all of my editing. I'd rather not do either.