Hello,
Yes the material quality is set to high. I did not have this issues on 4.8 with mac 10.10 (I am on 10.11 now).
Like I said the material / texture quality is good (editor, persona, blueprint preview) until the game play starts. So it can not be the graphic card.
The artifacts like on second screenshot come only in editor viewport.
Graphic drivers on mac are always the latest.
I think these are two different bugs: material quality drop and artifacts.
So there are two possible reasons for this issue:
- Changes in 4.9
- UE is not compatible with new mac 10.11 yet (I can not test 4.8 here)