I've tried a 32gb one i used for my wii u and say's it is write protected. Tried one from my phone, same thing. Now i just bought one at best buy, 64gb, not touched at all, formatted to fat32 and still same thing. I'm testing Mii Maker by saving a QR code and loadiine. All pins are properly placed, not moved and didn't even touch the pin of my new one. Using 3 separate micro sd adapters too. PC has no problem reading and writing to my sd cards. Also normal SD Cards work with wii U. Warning: Spoilers inside!