Using point() with small strokeWeight(1) or smaller may not draw anything to the screen, depending on the graphics settings on your computer. To fix this, you can 1) use set() instead, 2) use a larger strokeWeight(), or 3) draw the point using circle() or square() instead.
As per Ben Fry suggestion:
https://github.com/processing/processing/issues/5957#issuecomment-575353739