Do I understand right: When you export a PDF from LayOut and view it in Adobe Viewer everything looks as it should?
What do you mean by rasterized? Irregular blocky black outlines? That is a bug that seems to haunt Mac users with certain AMD graphics cards. The developers are looking for a fix, but it might be a Radeon driver problem (as your seeing the same in another application suggests). This is discussed at length in Black areas showing up in 2017 Layout viewport - #12 by Anssi.
Anssi