No 4k through hdmi splitter

[afonneland]

I have my apple tv connected to an hdmi splitter. It splits into a signal to my LG C7 and a videograbber for ambilights.
I was able to set the videoquality on apple tv to Dolby Vision before I started using the splitter and the grabber. But now the highest quality that shows up in the quality menu is 1080 hdr.

The splitter is 4k, the cable from apple tv to splitter and from splitter is 4k. But the videograbber is not 4k. Is it the grabber that screws things up?

 

[HobeSoundDarryl]

Temporarily unhook the grabber. Check the quality menu. 4K option showing?

Hook up the grabber. Check the quality menu. 4K option not showing anymore?

That simple test should tell you.

Bonus: assuming the above does tell you, swap the connections. If grabber was on "B" test it on "A" (connection). Maybe there's a sensitivity to one more than the other?

Bonus #2: if grabber does not have a built-in cable, try another HDMI cable just to rule out a faulty cable.

An extra experiment that might be interesting: unhook grabber, start sending 4K video, hook up grabber. Did the 4K downgrade to 1080p or did it just need to get started at 4K?