Okay, I'll list this out now I've experimented quite a bit. 1) In 2019 (beta / final (whichever), switching to an EGPU crashes Unity on MacOS whether Mojave or High Sierra. 2) When selecting the inspector whilst using the CPU or GPU lightmapper Unity will crash. 3) When baking the inspector UI will often erratically bounce up and down. 4) When an object is selected in scene view backgrounds will flicker black. 5) Post processing stack causes a "metal compiler error". 6) HDRP will bake the original procedural sky material whether HDRI is selected or not. 7) Volume settings are not saved when exiting and then opening Unity again. I've just tried out Unity 2018.4 LTS with HDRP preview (of course in case it was me being silly), I haven't yet experienced a single issue and nothing above has happened in the same test scenario.