This is not a hardware issue. That cyanogenmod supports it in some cases is because it makes certain choices.

For mass-storage we need to have a separate FAT partition to have it work on all OS's. This then needs to be unmounted/remounted on demand. Measures need to be taken that programs don't block those actions. Nor panic when the FS they plan to use disappears. Then there are the issues with buffers, possible file corruption, ...
Other impact is that the user will have hacked up storage etc...

This is why everybody has been moving away from mass-storage and onto MTP as removes the problems with multiple access etc.

And as I explained before, MTP used to work on OS X at the time we made the decision. And we are working on a solution for the only broken OS out there...