I'm not sure if this has been mentioned before: The 64GB micro SDXC cards work fine in the Jolla when formatted as standard FAT (i.e. FAT32). The belief that FAT32 is not able to handle such large partitions comes from the fact that the Windows disk format utilities cannot format such large partitions. However, using the Disk utility in Ubuntu, and formatting as 'FAT' there works fine, and reads correctly on Windows, Jolla, and Ubuntu (and presumably other distros). (Notice the FAT32 maximum volume size and the note in wikipedia.)