I'm using the old 64gb Sandisk from my older Razr M. I bought a new Sandisk 64gb card and cannot get my Pictures and Music copied over. I've tried formating every which way and no luck. I have a few 64gb cards, mostly Sandisk and one Samsung and none of them work for me. I even tried to format from the command prompt and from the phone with no luck. I've bought many cards from eBay, all new, but they are all have bad FAT's even after a fresh format.
I have a backup copy of my card on a external drive and copy to my laptop's card slot with an adapter and sometimes strait to the phone, and get "can't read file or SD card errors.