Why does my TV screen turn to bright green when I select 4K SDR on my Apple 4K TV device?

Just bought an Apple 4K TV device. My TV is a Vizio D65-E0 and it supports 4K SDR. I have an HDMI cable feeding into our AV receiver and then sending the signal to HDMI 1 into the back of the TV. HDMI 1 is the input which allows for 4K content to be displayed. Right now, I can only get 1080p SDR. The cables should be fine because I was able to display 4K content on my previous streaming device (non-Apple).