DBP repository

I experienced this weird issue myself that I couldn't create files or folders on the second SD card slot, even as root. Try experimenting with different file systems or format yor card on a different computer.
I found that when I didn't have write access on an SD card it was when I inserted the card into a different pc and didn't remove it safely. I have never seen this behavior on a different device but purposely safely removing/ejecting the card always made it work.