i am currently having this issue as well and corsair takes forever to reply me, also saying it was replied while nothing showed up...
anyway, i downloaded the latest firmware from moderator James and managed to get the keyboard to work but it is so unstable, after switching it to usb2.0 the ghosting issue seems to be fixed but now another issue had arised.
Whenever i restart my pc i loss the use of my keyboard again. and at this point its all random, sometimes a shutdown and reboot may get my keyboard back a few minutes after window starts or it will not at all.
i don't know what else to do and waiting around for them to reply my ticket is silly, its friday again and they're gonna make me wait till monday at least to get a reply.