No 4k on apple tv

Sorry if this is posted in the wrong forum.

So I’ve got my ambilight setup like this:

Apple tv 4k —> hdmi 4k splitter —-> splits into tv and hdmi to avi converter for the videograbber.

Before when my apple tv 4k was directly hooked up to the tv, I could change the video format on the apple tv to 4k dolby vision.

But now when it goes through the splitter, the best quality that shows up is 1080p hdr.

Anybody else got apple 4k to work correctly with ambilight?

I’ve got another 4k splitter, can I put that one in connections somewhere to solve the problem? If so, where would i put it?