Why won't my SD card mount.

A

AC Question

I have a rooted Blu Studio Energy 2 and a PNY 64gb MicroSD card. The SD card is mounted by TWRP flawlessly. I even performed a full backup to the SD card, put the card in my computer and all of the backup files were present. (The card is formatted with exFAT by the way.)

However from within Android, the card does not mount. I have the "SD card is not inserted" message. It can't be any of the hardware because TWERP did fine. What's going wrong with android?