The photos show it's stuck on luma value 9. I doubt it's the 4050. More likely it's saturated luma at the HDMI converter which is expecting a lower voltage range than the 800 provides.
A simple test to vindicate the 800 is to try the RF output on a TV which accepts the old analog standard.
A possible workaround is to wire a pulldown resistor to the 800's luma output. Maybe 75 Ohms to ground.