I've been using my Roccat Kulo for a while now and never had problems but recently it stopped working.
Sometimes it would work again when i unplugged the usb cable i usually use then plug it in normally (which doesn't let me use the headset at all) and plug in the usb cable again but that also doesn't work anymore.
I somehow solved the problem once but don't know how i did.
But Teamspeak tells me that it uses the Microphone (2 -Roccat Kulo) whereas before it used Microphone ( Roccat Kulo) which seems to work fine and also worked when i fixed it once.