I had some issues with corrupted exFAT partition that Disk Utility said it couldn’t repair.
Then I finally found a solution.
Run following command in terminal
sudo fsck_exfat -d disk2s2
disk2s2 is ExFAT partition.
Then it will ask you
Main boot region needs to be updated. Yes/No?
Now, You can then run repair in the OSX Disk Utility and the partition should be restored.
Isn’t it Easy fix ?
But Why ExFAT and NTFS support is so bad on Mac OSX?