no landscape using AV HDMI iPhone 12 Pro Max to TV

When I connect my iPhone 12 Pro Max to my TV with the AV HDMI adapter, it will only display in portrait mode. when I rotate my phone the screen on my TV stops updating when my phone display changes to landscape (widescreen). I still have sound coming, but my phone seems to quit sending video over the HDMI. when I rotate the phone back to portrait, it begins to send video back to the TV in portrait mode again.

why won't it work in landscape? My iPad mini works fine with all of the same equipment, but my iPhone 12 Pro Max (and my wife's 12 pro max also) will not work in landscape mode connected to the tv.

please help! this is so frustrating! every video and article I find shows it working just fine and nobody seems to have this problem that I can find!