Unfortunately, the MP3 player does NOT support SDXC cards out of the box. An SDXC card is any SD card with a capacity of 32GB or more.
In case you're curious why this isn't supported, all SDXC cards come pre-formatted with the exFAT file system. This file system is a Microsoft proprietary system and would require us to pay for additional licensing to support it.
One thing you can try doing is, re-formatting your SDXC card to the FAT32 file system and it will likely work. I will give this a try myself and report back.