To use an SD card with Circuit Tracks and Circuit Rhythm it's recommended that the SD card used is formatted to FAT32. Some cards of a larger capacity may default to exFAT format and so in some cases, it may be necessary to format the card appropriately. 

This article gives instructions for both Mac and Windows. In both cases, the card will need to be inserted to a card reader to do this - it cannot be done via the Circuit Tracks/Rhythm.

It's recommended that you use the latest firmware as there are changes to improve support of SD cards. 

Note that formatting a card removes content stored on that card.

Windows:

To check if the card is in the appropriate format, go to the File Explorer, right-click your SD card on the left-hand side and click "Properties":

Go to the File Explorer and right click your SD card on the left-hand side, then click "Format..."

Set the File system to FAT32 (which in this case was the Default):

On larger SD cards, FAT32 may not appear as an option here, in which case follow these steps:
Note that if you are not experienced using the command line it may be better to contact support for assistance.

• Press Windows key + R key.
• In the Run box, type "cmd" and press Enter.
• In the cmd window, type "diskpart" and press Enter. The diskpart tool will be opened.
• Type "list disk" and press Enter.
• Type "select disk #", where # is the number of your selected disk. Then, press Enter.
• Type "list partition" and press Enter.
• Type "select partition *" and press Enter.
• Type "format fs=fat32" and press Enter.

If issues continue after formatting try the SD Association's own formatting tool: https://www.sdcard.org/downloads/formatter/sd-memory-card-formatter-for-windows-download/ 

Mac:

To check the format of the card, go to Finder and right-click the SD card, then click "Get Info":

To format the card, go to Finder > Applications > Utilities > Disk Utility:

Select the SD card and click "Erase". Then select the FAT32 Format.

If FAT32 is not available as an option, follow these steps:

Note that if you are not experienced using Terminal it may be better to contact support for assistance.

1. Go to Finder > Applications > Utilities > Terminal
2. As there may be other cards or storage disks connected to your Mac, we need to identify the card. To do this type the following command into the Terminal window: diskutil list
3. All the available storage devices will be presented in the form of a list.
4. Identify your SD card and take note of its identifier (i.e. /dev/disk2).
5. Now, to format the SD card to FAT32 on MAC you need to type the command: 
   sudo diskutil eraseDisk FAT 32 SDCARD MBRFormat /dev/[disk identifier]

If issues continue after formatting try the SD Association's own formatting tool:  https://www.sdcard.org/downloads/formatter/sd-memory-card-formatter-for-mac-download/