I formatted the card with both the PC and the phone to exFAT, but unfortunately, after loading a large amount of data (more than 4GB), certain files disappear after inserting the card to the phone. If I paste more than 4GB of data, it takes minutes, followed by hours.
How do I solve this problem? Did I purchase a fake card on Amazon? I am using a Sandisk Ultra Micro SDXC card in a Verizon Samsung Galaxy S4.