[Verizon Samsung Galaxy S III] lordazoroth:
Ok still not mounting properly.

Here's what I did:

Typed "echo $SECONDARY_STORAGE" in a terminal emulator, showed "/storage/sdcard1"

Typed "blkid", showed "/dev/block/mmcblk1p1" only when sd card was inserted under fat32 file format

Formatted sd card to exFAT on PC, inserted back into s3

Flashed CM10.1_exFAT-mountsd_2.0_HMkX2.zip

Ran terminal emulator, typed su >> exfat-mountsd.sh got this:

u0_a70@android:/ $ su

root@android:/ # exfat-mountsd.sh

[exfat-mountsd v2.0] exFat autorepair and mount script for CM10.1 (HMkX2 CORE//XDA)

Automated mounting script for exFat on GS3

/storage/sdcard1 is not mounted. (OK)

Calling [fixmyexfat] on /dev/block/mmcblk1p1 (if needed)

Broadcasting: Intent { act=android.intent.action.MEDIA_CHECKING dat=file:///storage/sdcard1 }

Broadcast completed: result=0

[fixmyexfat v2.0] exFat header repair tool (HMkX2 CORE//XDA)

More robust than before!

Usage: /system/xbin/fixmyexfat.sh <block device, eg /dev/block/mmcblk1p1>

[fixmyexfat] Manual target is /dev/block/mmcblk1p1

1+0 records in

1+0 records out

512 bytes transferred in 0.166 secs (3084 bytes/sec)

Segment 1 (0:4) (BAD)

4+0 records in

4+0 records out

4 bytes transferred in 0.012 secs (333 bytes/sec)

Segment 2 (484:4) (BAD)

4+0 records in

4+0 records out

4 bytes transferred in 0.007 secs (571 bytes/sec)

Segment 3 (508:4) (BAD)

4+0 records in

4+0 records out

4 bytes transferred in 0.005 secs (800 bytes/sec)

Check complete!

Check complete, mounting and initializing...

########################## ATTEMPTING COMMAND ##########################

mount.exfat-fuse -o rw,dirsync,umask=0 /dev/block/mmcblk1p1 /storage/sdcard1

Attempting bypass...

* daemon not running. starting it now on port 5038 *

* daemon started successfully *

connected to localhost:5556

List of devices attached

localhost:5556 device

Running ADB commands

FUSE exfat 1.0.1

ERROR: invalid VBR checksum 0xa04b8eb5 (expected 0x804d6ce4).

Broadcasting: Intent { act=android.intent.action.MEDIA_MOUNTED dat=file:///storage/sdcard1 }

Broadcast completed: result=0

Process complete!

root@android:/ #

Not sure how to read this...

Afterwards my notification panel says: "Damaged SD card : SD card is damaged. Try reformatting it."

Tried restarting s3, mounting in storage settings, reformatting in PC. Ran script 4 times on a fresh exFAT format with the same notification error (format was unrecognizable by s3 and PC after running terminal command "exfat-mountsd.sh" [don't worry didn't lose any data :P]).

After each format to exFAT on my PC I placed a few images on the card to ensure it was functioning properly, /storage/sdcard1 directory is always empty.

Mounting in settings >> storage generates the same notification error: "Damaged SD card : SD card is damaged. Try reformatting it."

Any ideas?... it is detecting an SD there after mount attempts (despite exFAT format) interestingly enough. :D Though nothing is detected after a reboot unless another script or settings >> storage mount attempt is performed.

I should mention that I ran a "quick" format when formatting the SD card from Fat32 to exFAT, not sure if that might be relevant.