Powerpoint 16.15 (180530) Save as PDF - images are blurry

Result:

I did as suggested, working with an Illustrator file and adding a tiny JPG to the file before Export. 

After Inserting in my PPT 2016 on the Mac and following the operation for resizing and Cropping, then opening in PPT 2016 for Windows, the graphics issue appears to have disappeared.

HOWEVER!  For sanity reasons, I remade another graphic in the "old way" that had shown the black, chunky outlines when opened in PPT 2016 for Windows, and placed that in the same file (along with the "new way" using a JPG), and this second file also showed up perfect in PPT 2016 for Windows!

So...I have good looking graphics now, but...what was the original problem?  Was it something like a fluke?  Or is there something else at play here?  Could it have been that at the time I was working on my original files, some corrupting feature/code was running and all my output was getting affected?  But restarting the program somehow fixed the issue? 

The problem still exists that one can never know if it is "working" or not, unless you create the graphics/slide, then open up in another Operating System, to check the result.  And that IS a lot of extra work when designing in PPT 2016 for the Mac, to not be confident on whether your graphics/layout will translate to PPT 2016 for Windows correctly.

I will update this issue if I learn anything more.  Thanks!

Thank you for this quick response.

Just to be clear:  the original graphic in example #1 was fro Illustrator, but the graphic is example #2 was drawing in PPT itself.

And, my import process is: create in Illustrator, Export as .emf, Insert .emf into PPT, resize however needed (because its a vector!), then copy/"Paste as Picture," then delete originally inserted .emf, and place the copy/pasted version into the same—now vacant—spot, and the Crop the edges down to the artboard.

I can try what you suggested with one of the graphics causing this issue, go through the whole operation, and then see the result...and report back.  Thanks!

I also notice that the text in the Windows screenshots is a bit raggedy-edged.

I have a hunch that you might want to test against.  In some situations, PPT will render bitmaps with the fewest possible colors, which can cut down on image size considerably, but if it knocks the colors down to 8-bit (256-color) or less, it can't create enough colors to antialias (smooth) text and shadows and such.

This may or may not work, but it's worth a go ...

Before moving your image from Illo to PPT, add a tiny JPG as part of the art.  It can be the same color as one of the other shapes in your art and just a few pixels, so it's invisible.

Make sure it's also selected when you copy/paste to PPT.

Because JPGs are necessarily 24-bit color, this can sometimes force PPT to handle the whole graphic as 24-bit, which can ... I can't promise WILL, but certainly CAN ... make the results a lot smoother.