Not all HDMI ports are created equally. Right now, you’ll commonly find HDMI 1.4, 2.0, and 2.1 ports on your TV. To pass 4K content, the port, cable, and source need to be compliant with a protocol called HDCP 2.2. If your TV won’t display 4K content, it’s possible you’re plugging into an incompatible port. Try another one or check the manual on your TV to see which ports you should be using for UHD.