I bought one of those 64gb cards and it was defective. They are not legitimate SD cards. Legitimate 64gb SD cards are "SDXC", not "SDHC" or "SD" cards. The specification does not allow for "SDHC" cards above 32gb therefore not only are they very low quality and very prone to failures, they won't work with some devices because they do not meet SDHC/SDXC specifications.
Thanks for the heads up! I'll definitely steer clear