SanDisk Ultra 64GB Ultra Micro SDXC UHS-I/Class 10 Card with Adapter (SDSQUNC-064G-GN6MA) [Newest Version] no, the card is not fake (bought from bestbuy, all 64GB can be written to perfectly fine on a PC) and all fake card test programs pass. yes, the card was formatted to fat32 with 32kb clusters (i've done this many times before with other sd cards with no problems) So far I've tried formatting with easus partition master pro and guifat32format. This is especially frustrating since I just returned a 64GB SDXC that did have bad blocks (maybe a fake) BUT DID WORK ON 3DS. Now I got this new 64GB SDXC card today (a SanDisk ultra micro w/adapter) and isnt even detected by the 3DS! This is so frustrating! Any miracle formatting tool im not aware of. I thought the ultra series would be compatible for sure. and if my card simply isnt compatible and cant be fixed by formatting, how about a list of confirmed working 64GB and 128GB SDXC on 3DS?