Hello,
this can be related to the cardreader or usb slot you used to read the card with the computer. if it supports only SDHC cards up to 32GB then putting a SDXC card in there it will prompt it to format it to fat32 and then of course will be limited to the 32gb capacity as you already saw.
here you can find some more info about the sdxc and sdhc formats of the card and the different capacity limitations that they have
