I would definitely report a bug, but in the mean time, here are a couple of buttons you can use.
I edited the RB, set its initial state to Selected so I could see it filled in without handles. Then I formatted it to what I needed (Edit the colors, and change the corresponding Accent color, if there is no style color you like. Just be aware that will probably change every use of that color.), and used a snip tool to capture it as a graphic. I edited the button, duplicated a state, deleted what was there, and pasted the graphic.
I don't know if you want to do that much work, but it isn't any more work than placing a circle, and once done can be reused.
