I'm using a 64gb SanDisk Extreme micro sdxc card in my s9+. Worked fine until recently. Device failed to re-format it. Tried it on my mac (OSx El Capitan 10.11.6) using a reader and disk utility, and realized I had only one file system option: fat32. Tried twice, failed. Even if it had succeeded, I would not have wanted to be limited to 4gb files. It sounds like android takes sdxc cards in exFAT, but I'd like to confirm with someone. Google holds no answers it seems. If so, how do I format it using my mac? The s9 won't read it at all now.