SD card read problem on WIO Terminal

I am trying to load and read back WAV audio files from the SD card on a WIO Terminal.
I am using a 16GB micro SD card. I have tried both FAT32 and exFAT formats.
When I execute the Arduino Seeed_Arduino_FS “listfiles” example, the listing
comes back as empty. I can see the WAV files I loaded when I mount the SD card with my Mac.
Anyone have an idea on why these files do not show up in the listing?
There are no errors, just a listing that shows no files in the “/” root folder.

Thanks

-Joe

Hi, @jkuzma2940:
there exists a demo code in our github that describes how to use the code to list file.
if you want to list the sd card context you need uncomment the macro at https://github.com/Seeed-Studio/Seeed_Arduino_FS/blob/master/examples/listfiles/listfiles.ino#L30

//#ifdef USESPIFLASH
 #undef USESPIFLASH

That works!
Thanks a lot.