I did some further testing and run into a display issue. Of course I have no idea where this coming from.
Blender starts by default with the Display Device sRGB.
I re-rendered an old test scene that I made a while back for the Blender&ACES guide on my website.
The image contains all the colors from the color checker and the rendered result looks like this:
Only the cyan sphere in the viewer is broken. The shader uses the acescg values from the ColorChecker2014 cyan patch 18. And this is the only ACEScg value that is out of gamut in linear-sRGB/Rec.709.
The EXR render is of course fine and that this issue only seems to appear with the sRGB display transform. When choosing the Rec.709 instead the render view looks fine and identical to the same render view with the old OCIO v1-ACES 1.2 config.
Furthermore I found out that the PNG writer from Blender is writing out a broken image too in this case, the JPG writer works fine.
I setup a new page on my website on how to use the new config in Blender and I will check where I can report this bug.