Apple TV 4th gen force RGB

Hi,

I have a unique problem. I am trying to connect an Apple TV to a Blackmagic Capture Card that is attached to a server that runs a video wall. The Blackmagic card only supports the RGB colors space and will not work with devices that use the YCbCr format. I was please to find out that you can manually change the Apple TV to use the RBG space in 4K SDR. Unfortunately, when I try to change the Apple TV to 4K SDR it defaults to YCbCr resulting in the card crashing and the settings reverting back to 1080p before I can change the color space. For some reason the card accepts 1080p HDR (I believe operating in the YCbCr space). Any thoughts on how to change this and have the settings stick? I tried using a separate 4K TV to change the settings but the Apple TV reverts back when it detects a new device. Any help is appreciated.