I've had almost exactly the same thing happen, although I'm running Windows 10. Have been using it happily for months and it has stopped working. It doesn't seem to be a port issue as if I plug my monitor into the same ports it works fine. I've tried both HDMI and DisplayPort. I get a green light on my headset, but not display. If I select mirror display i can see what should be on my headset on my monitor and it's tracking. Interestingly enough if I disable direct mode, the right hand screen on my headset will display my desktop. So the cable appears to be working fine in so much as I can get an image on my headset, just not the one I'm after. Might be worth checking to see if changing the direct mode seeting and seeing if you get an image on your headset. I've done same things you have done and still no luck.
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