as far as I'm aware, the galaxy player will only work with cards up to 32GB, or SDHC cards (which it quotes on it's website). I'm not sure SDXC will work in the device.
I know that SD and SDHC cards have the same contacts, but SDHC cards don't work in an SD card reader.
I'm pretty certain that SDXC will have the same problem in SDHC devices.
I know that from cameras (which I sell) the camera must be enabled to read SDXC cards. You can format it to any format you want, but it's the device you use it in that still has to be able to read it. If it's beyond the capacity of the device it will not register, show card error, or show no card in device.
Let us know if it works though!