Strange Artifacts on Shape

In the last couple weeks, I’ve been seeing strange diagonal lines appear on button instances. These are not in the master component. The shape is a rectangle that I’ve made into a circle with a large corner radius. if I reduce the radius by just 1 pixel lower than what is necessary to make the shape a circle, then the strange artifacts disappear. They only occur when placing a new instance, and instances that were placed before are still OK.

Aside from reconstructing the buttons, any thoughts on correcting this?

Just bumping this to see if anyone has experienced the same thing.