Since updating to the 2019 version of Illustrator, I am having this issue with the stroke that crops up randomly for certain elements.
On applying stroke, the stroke on the left doesn't show up on random elements. I used the eyedropper tool to make sure that no properties were different and even then, the problem persists.
As you can see from the stroke on the innermost box, the stroke goes around it. But even using eyedropper tool from that box renders the missing left stroke on this particular box.
Here's the funny part. When I take the buggy box as the reference for the eyedropper tool and copy the style to some other rectangle, that renders properly.
Any ideas why this could be happening?