might try two things
1 -- a different HDMI cable
2-- with the XBOX hooked up and running power cycle ( unplug the TV ) for a few seconds
One thing I discovered when I installed my Ultra was that an HDMI cable that seems to work OK, may in fact not be working correctly. Now, you're not dealing with 4K video, but it's always possible that the cable you think is working fine might still have a flaw. My cable seemed to be working fine, but after replacement and curing of my 4K issues I realized there were a few issues that I had kind of dismissed as nothing, but were in fact a cable issue.
You don't need to buy uber-expensive cables. I bought a two pack of 3' Amazon Basics HDMI 2.0 cables for under $10, and all my connection issues went away.
Hey I found this video on youtube. It might work for you. I am not sure though. There are alot of issues like this on google too. Let us know.