If I’m remembering correctly, some other people had an issue with this and I believe that the dnsound files do work via transfer, but that the sysex wasn’t going through. I can look for the thread, I think that there were actually a couple discussions on it but I haven’t tried this myself.
I think that this was the more comprehensive discussion but not sure, I read a lot of posts on here.
Anyways good luck, hope that works out for you.