Model: 3820EU - Streaming Stick 4K
SW Version: 10.5.1 - build 4066-CU
TV: LG OLED (EF950V)
Display setting: 4K HDR HDCP2.2
App: BBC iPlayer
Version 1.0 - build 91000031
Problem:
On any BBC 4K HDR content, the colours are blown completely i.e. massively over-saturated. Makes the app unusable, and the Roku stick, well, not very useful.
Reproduce by playing any UHD content from the iPlayer App, particularly Green Planet, or the Ultra-HD test loop.
It looks exactly like the HEVC-4K-HDR problem where the Roku stick forces a BT.2020 colour space inappropriately when BT.709 is specifically flagged ref: HEVC 4K HDR colour problem so I suspect it has a similar root-cause.