I’m using an Anker USB-C to HDMI adapter (https://www.anker.com/products/variant/usbc-to-hdmi-adapter/A8306041) to connect my 13" Macbook pro to a TV. The TV is capable of displaying a 4k image at 60Hz, with Chroma 4:4:4 - and I sometimes see this working correctly (verified using this image: http://i.rtings.com/images/test-materials/2017/chroma-444.png).
However, a lot of the time, the test image doesn’t display correctly, indicating I’m not seeing a 4:4:4 image.
I’m not sure if this is an issue with OSX, Macbook Pro, Anker adapter, or the Display. I have changed the cable so I don’t think that is the issue.