HDMI has always been a shitshow. I spent years of my life playing whack-a-mole for a major set top box manufacturer because of incomplete or braindead implementations. CEC added a whole 'nother layer of shit to go wrong. There is a reason CE mfgs go to "plug fests"(https://www.cta.tech/Events/CTA-861-PlugFest) instead of being able to trust their implementation will work with other devices as long as they follow the rules.