New "no signal" problem with Xbox Series X on Hitachi TV

I booted up my Xbox Series X for the first time on Thursday. It worked fine on my Hitachi TV. It downloaded games overnight. On Friday morning, I try to start it up, and get the "no signal" message on screen. Here's what's weird:

1. The Xbox Series X still works on other TVs, but not on the Hitachi TV anymore.

2. Other devices (e.g., Chromecast, Roku) work on the same HDMI ports on the Hitachi TV that the Xbox Series X no longer work on.

3. I did factory resets of both the Xbox Series X and the Hitachi TV, but neither fixed the problem.

Any ideas?

Many thanks!

:)