Notes checklist displays black squares

sbezuk wrote in his post, "Checklist in notes shows black square when unchecked": Running High Sierra 10.13.2 on Mac Mini mid2011. When using an old checklist in notes an unchecked check circle shows as a solid black box. If I check the black box it changes to a normal checked circle. The checklist functions normally on iPhone 6 running iOS 11.2. Same happens if I start a new note on the Mini. Turning checklist on and off doesn't help.

I see the same problem on a 13" MacBook Pro late 2011, running High Sierra 10.13.3.

I have a Del P2415Q monitor plugged into the MacBook's Mini DisplayPort. When I drag the Notes window to the external monitor, the black squares appear in place of the standard round unchecked buttons. When I drag the Notes window to the MacBook screen, the standard buttons appear.

Hope you fix this bug. (I've seen it previously, but don't remember which monitor it appeared on at that time.)