I’m using a SanDisk microSDXC Card 64GB Extreme. I’ve formated it fat32 on my personal computer (just with regular windows formatting). Inserted it in the tablet and it worked ever since (for like the past 2 months) on Android and Windows. Haven’t had any issues so far. From what I’ve read it also depends a lot on the SD card. I’ve read a lot that people have problems with 128gb cards, that’s why I only bought a 64gb. I don’t know, maybe I just got lucky.