Connecting Radha Zero to Waveshare 7.8inch Hdmi Display

Hello i’m trying to connect an e-ink display via the HDMI port but the display seems to flicker between black and white and not display the image.

I confirmed the display works by plugging other computers in, which all work just fine.

Is there anything that may be causing this issue?

What OS? The product wiki indicates you need to set the refresh rate to 15Hz or less. They also provide HDMI timings for RPi. Have you configured the Zero to output an image format that the display can use?

It’s running latest version of Debian. I added a new image format using xrandr but the display still flickers