anyone having issues with using 64 gig cards, here is the fix
Originally Posted by badf1sh
I also had the same issue with a PNY 64GB SDXC card. Apparently the Windows formatting program can only handle a FAT32 partition up to 32GB. I used the free program guifformat to format my card to a 64GB FAT32 partition. Worked like a charm for the formatting, however I will have to wait until this evening to try it in my Garmin.
Garmin specifies FAT32 as a requirement for formatting and lists 64GB as the max for the 76XX series, so I'd imagine the exFAT formatting of the card was the issue.