I went through three different cards myself, and I can only say that my phone fried them all either with a bad corruption on the card itself or a bad card reader on the phone.
I know that all three cards were good..but once inserted, they could not be read by the phone and another devices, e.g. camera, pc, mac, etc.
Ultimately, I changed immedately the device - through a warranty exchange and toss the cards in the bin and in one case sent back to the vendor for a warranty exchange.
I have no clue still on what would cause this...