I'm working on a map in ArcGIS Pro 2.4.1 in which I have a layer with 50% transparency. Here you can see what the color of the polygon is and how it appears in layout view with the transparency:

When I export to PDF, I get this:

Same results with JPEG and PNG.
Question: Anyone know why the transparency isn't being preserved during the export to PDF? Thanks for any help you can provide!