Hello everybody, I have that problem too. On the Mac, the 128GB Samsung EVO cannot be read on the Windows computer, but it can. I still have a 64GB EVO card, but it can be read on the MAC. Is there a solution?
Update: tried serval SD cards (that have been working in my other cameras and devices) and tried mac os and windows. No success. As soon, as the a800s has formatted the cards, they cannot be read anymore in any computer. I think the formatting algorithm does not create the mbr and/or partition correctly. This is awkward.
I tried 256 card I have same problem on macbook I try to format card to exfat - mai70 after inserting card wanted to format card two Than I format card to fat32 on macbook, after inserting mai70 want to format card and I agree: after formating on macbook, than on mai70 - a have card that mai70 can write and macbook can read