ok, the in the current OpenGL implementation actually ueses features of OpenGL4.2 and 4.3, as discussed in this post:
“Unfortunately in order to use in the current UE4 OpenGL implementation we need some 4.2 & 4.3 features/extensions that aren’t present on the Mac (yet). This is something I intend to look at & get working, but there’s no timescale.”
Again, I’m definitely interested in what @marksatt-pitbull says he intends to look at 