Having trouble transferring SD card files to bigger SD card

I recently bought a Japanese 3DS LL (XL) for my girlfriend, modded it, and changed the language to English as a Christmas gift. At the time, I only had a 3GB SD card, so I used that for the modding. Now, I want to upgrade to a 32GB SD card, but I’m having trouble getting it to work.

I transferred the files from the old SD card to the new one, but when I put the new card into the 3DS, it doesn’t work. I’ve tried everything I can think of including different ways of formatting and the only potential issue I can come up with is that I originally used a Windows PC to mod the system, but now I’m using a Mac to set up the new SD card, as that’s all I have access to right now.

Has anyone run into a similar issue or have any advice? Any help would be greatly appreciated