RPi4 4k content colour problems

Hi,

Long time lurker but first time poster here, hoping someone can help me out.

Some background: I've had my RPi4 running Hyperion to drive a few Phillips Hue lights for a while now and everything was working fairly well...until I dragged myself into the 21st Century with a new 4k TV. I have upgraded my HDMI splitter to as my existing splitter and HDMI to RCA adapter only supported upto 1080p. The splitter claims it can provide 4k to one device and 1080p to another if required (with some caveats about not being able to support HDR in some cases but I'm willing to live with that for now as the HDFury boxes are outside of my budget) so I've kept the 1080p HDMI to RCA adapter that was working previously.

As it stands:
- If I push a 1080i source (any HD channel on Virgin Media) to the splitter the TV and hyperion work as expected
- If I push BT Sport Ultimate (4k HLG HDR I believe) I get a 4k HDR picture on my TV but no signal to Hyperion. I think this is expected as there's a caveat in the splitter's docs that say it will send a picture to just one device if the screen attached to HDMI1 is being provided with, and able to use, HLG or Dolby Vision but the other devices can't support it, and obviously my 1080p HDMI to RCA doesn't support HLG. Thus, I get a HLG picture on my TV but not Hyperios
- If I use either the Netflix or Amazon Prime app from the Virgin Media set top box I get a 4k (with or without HDR depending on the choice of show) picture on my TV but the screen grabs in Hyperion have a green cast across them. Some purple shows through but other than that the grab is void of all colour as shown in the grab below

Has anyone come across this before? More importantly, does anyone have a fix?

Until either someone produces a more affordable equivalent to the HDFury boxes or I bite the bullet and just pay the price for one, I can cope with the fact that my current cheapo splitter won't work with HLG content and the fact that it appears to insist on using HDR10 rather than Dolby Vision but the green cast across all Netflix or Prime video content regardless of whether the show is in 4k, HD or SD, is rendering it a little useless.

Thanks

I got there in the end. After digging out my old 1080p TV and attaching that to the splitter too it become clear that if the 4k TV was attached to HDMI1 of the splitter all outputs were receiving 4k signals (I'm amazed hyperion was showing any picture at all in that case as my 1080p TV just gave an 'unsupported input' error). Moving the 4k TV to any of the other HDMI ports allowed me to get a 4k picture on the new TV but still see a downscaled 1080p image on the older screen...and finally get a full coloured image in hyperion.

It's not quite the HDFury but the splitter now lets me have 4k TV with ambilight including HDR10. I'm currently sacrificing Dolby Vision (Netflix and Prime Video revert to HDR10 instead) and HLG (I get a 4k BT sport Ultimate picture but no HDR). The splitter's docs talk about having the ability to disable all but the HDR compatible screen's output using a button on the splitter box itself which then allow's Dolby Vision and HLG but disables ambilight as it has to stop the HDMI output to the non-HLG/Dolby Vision devices. I haven't played around with that yet though.

I'm happy enough with it given it was a fraction of the price of an HDFury box.