Anomaly when expanding elliptical stroke in illustrator

I keep running into a strange issue when I am expanding the stroke of a one pixel ellipse in illustrator. It creates unwanted anchor points on the expanded shape. See image:

Has anyone else run into this issue? I can't seem to find the cause or a solution. Is it a glitch? I'm using Creative Cloud AI v 18.1.1.

A few things to note:

• I'm not using 'Align to pixel grid' and it doesn't help when I do.


• I've tried redrawing other ellipses, and they still have this problem.


• It also happens on oval ellipses on occasion