I saw something somewhere (sorry cant recall exactly) person with same/similar question and that a reformat did the job. I want to say they reformated to fat32. (universal catch-all IMO) I just wrestled down the ridiculous root process for the 4.3 upgrade, so formated a couple of sd cards to see what if anything popped up at me. ext2/no (micro and sd10) , ext4/spotty (micro sd/yes, sd10/no) , fat32/yes (micro and sd10)
I just migrated to sprint from verizon so still getting my feet wet with /dev/d2spr. Im no stranger to the bootloader/bypass/bullsh*#, so knox and what they are trying to accomplish with making sprint more enterprise friendly may be some source of further exploration into why changes are here and moving forward.
For we linux-minded / gparted is just a right click and refresh away... hope this helps. just remember to refresh encryption efforts (if applies to you) Some crypts are friendlier to some formats than others. dont want to think something is secured when it isn't ....anymore.