A known issue of s3 with Sandisk sd. I suggest using the built-in Windows Disk Management tool to completelly delete card's volume (notice that there is a hidden partition of 10Mb in the card, separated from storage partition that should also be deleted- the partision manager should show them both).
After deleting and merging both partitions as one unalocated space, format it all by using exfat method.
A word of procution- I recommend to do this when the micro sd is connected directly to your pc using a sd card reader- just to make sure you won't delete phone's internal sd by accident...
Last edited by amirTor; 18th January 2014 at 04:13 PM.