I bought micro 128 GB sdxc and simply the lumia 640 xl don't see the item says sd card storage not found, he formatted my computer see it but the phone does not.
did you try to open Storage check (WP 8.1) or Storage (W10M) on the phone and see if that can format the SDCard? Also try a different SDCard and if that works I must assume it's the particular SDCard that doesn't work.