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?