Exporting to PDF/EMF Troubles from ArcGIS 10.3

[GerryGabrisch]

I have recently started having troubles exporting to PDF where certain colored circle marker symbols appear as black dots.

I have read the information posted here: 17783 - Diagnose an ArcMap printing or exporting problem  but get the following results when publishing as EMF.

If I export to EMF and view the resulting file in MS Paint the symbols appear as they do in ArcMap.

If I export to PDF from ArcMap 10.3 I get some colored dots appearing as black dots and others appearing as they should.

If I add the EMF file to an MS Word document all the dots appear as crescents.

Why is this happening and what can I do to fix the issue?

FYI, I do not have (or want) ArcGIS Pro.

Above is the original from ArcMAp

Above is the EMF as it appears in Word.

[GerryGabrisch]

I have in the past selected both the embed fonts and convert marker symbols to polygons options when exporting to PDF.

I have determined that un-checking the convert marker symbols to polygons option results  in a non-corrupt PDF.  What would cause this change of behavior if I have not changed/upgraded my GIS software?