OK, I'm beginning to scratch my head here as I think, like you, that this thing should just work like USB.
I think the best option, for now, would be to keep using the USB to hot-swap your HDD's and contact Gigabyte Technical Support as we seem to have covered all available options. It might turn out that there is something simple that we are all missing here and the only ones who can tell us are Gigabyte themselves.
Sorry that I can't help further but, if you can get an answer from Tech Support please let us know.
ATB