Got annoyed with the short cable and grabbed up all the stuff from that "Reality Check VR" video for 15 more ft of extra cable on the Oculus CV1.
Long story short, it refused to work, repeater and all. The CV1 indicated all good but the display would constantly blink on/off.
After downsizing the HDMI, it worked but this was not acceptable. Why then had I purchased the 15ft HDMI?
Then, while scouring the web, there was an reddit post which indicated that the Monoprice 15ft HDMI did not work for all, unfortunately.
Not to be defeated in my quest, the HTC Vive Link Box was bought immediately along with an 15ft Male to Male USB 3.0 cable & an Universal Power Adapter w/ interchangeable tips.
Now the 15ft HDMI recommended cable works but some spare 15ft/20ft Cable Matters HDMI cables did not.
My Pimax 4K screen went out so can't verify if the HTC Vive Link Box will work but it's worth a shot if returning it would not be an issue.