It looks like some 3D printers can not read GPT microSD cards. Or SD cards formatted as exFat. You can fix the problem by converting the SD card to MBR and create a FAT32 partition on it.
These steps are for windows, but the idea is the same on Linux and macOS
- Delete the partition on the card
- Change to MBR
- Create new Fat32 Partition
- Use in 3D printer
Insert the Micro SD card into your computer
Next open an Administrator Command Prompt. Search for cmd, right click, and run as Administrator.
Launch the WIndows Disk Part utility with
List the disk.
Select the Micro SD card with the following command. Replace 1 with the proper disk from the above command.
select disk 1
Now lets clean the disk. Warning! This will delete all data on the SD Card
We now have a clean SD card.
Convert the SD card to MBR
Create a new partition to use
create partition primary size=1024
You should be able to finish this using the Disk Management utility in Windows.
Format new partition and assign drive letter.
format fs=FAT32 label="3D" quick assign letter=E
You should be able to put your gcode files on the sdcard now.