Not sure if it has anything to do with the connections but try going through this article and see if you missed anything.
https://www.vrheads.com/how-enable-vr-elite-dangerous
Those were the steps I ultimately followed (no dice).
Sure enough, tried it again last night and this time I unplugged the HDMI output cable to my TV first. BAM, soon as I plugged in the headset I figured it was gonna work because the headset was active and showing that Steam/VR Home thing or whatever it is when it was blank before. I haven't used the VR a whole lot, and not in quite a while, so I'm rather a nub still at this.
But anyway I got ED fired up and it is pretty cool. Not quite as immersive as I thought it was gonna be but it was neat. Ugh, I can say that I like mouse & keyboard for control wayyyyy more than a joystick. I just gotta get used to the stick I guess.
One thing that's been kind of annoying since the start is that it's easy for things to be out-of-focus if I don't have the headset pushed up on my head and just in the right position in front of my eyes. That's my biggest complaint about the Vive (any current gen VR probably); things outside of directly in front of my eyes get blurry... I guess that's the term for it. I've tried adjusting the pupil distance with the knob on the headset but I think there's still some tweaking I could do. I'm gonna do some searches on the web and YouTube to see if there's some guides.