GPI Case2 Dock HDMI - Wrong Colours (splash pink/missing reds??)

[henryjfry]

I have a weird issue where the recalbox HDMI connection on the GPI Case 2 dock appears to have the wrong colours.

With the splash screen enabled it looks decidely pink on the rainbow splash when it boots via the dock and videos in Kodi are similarly not displaying the correct red levels.

e.g

I've tested numerous config.txt settings and cmdline.txt but I cant affect the colour, only the screen size.

I've tested with a different OS, PiOS on a different SD card and it boots the splash image docked and connected to the HDMI so its not a hardware/dock/cable issue.

When it boots off the dock to the LCD screen the colours are perfect, so its some combination of config.txt settings.

Can anyone help?