The problem is that only one RadioButton is shown because it doesn’t like having more buttons with the same name. The error:
Jan 14, 2020 6:00:45 PM controlP5.ControlP5 checkName
WARNING: Controller with name "/x" already exists. overwriting reference of existing controller.
Jan 14, 2020 6:00:45 PM controlP5.ControlP5 checkName
WARNING: Controller with name "/y" already exists. overwriting reference of existing controller.
This issue is somewhat related.
One ugly fix is to rename x and y to something like x0, y0, x1, y1. Was there a different way to give buttons unique ids but repeating labels?