So here's what I get when I attempt to Rebuild BS and all Files and Directories are successfully(!) discovered. I type Yes, and then go to Write, and here's what TestDisk prints out:

It prints out "Warning: valid FAT bootsector but not a FAT32 one!"
It should print out "Success! Valid FAT bootsector, it's an exFAT one! Woo hoo!"
How can I fix TestDisk's confusion in this matter?