I did have something similar a good while ago although my problem wasn't the HDMI connection it was the sensor that was continually disconnecting/reconnecting.....I traced it back to the USB HID identifiers conflicting with each other. I hadn't done a fresh install for a long time, had all sorts of entries within the registry for my USB devices many of which had been plugged into one USB port and then moved into another but over time this meant there were loads of rogue entries in the system that ultimately needed a good clean up.
My issues first manifested in my Fanatec wheel where it would only work in one particular USB port, then it started reconnecting/disconnecting and then the Oculus sensor started having similar issues. I can't recall the software now (may have been this one -
link) but I did a google search and looked for an application that would clear out the USB registry entries....once I'd done that and reconnected devices they are all back and working fine regardless of whatever port they are plugged into.
I'd also recommend removing and reinstalling the Oculus software too if you haven't tried that yet.