My colour options show as buttons instead of swatches. Why?

A colour swatch only paints when the option is a Colour or Shade option and the matching variant has a colour saved on it — by default a hex value, for example #c8102e.

Check that your variants have that colour filled in, and that Settings → Advanced points at where you store it. Options without a saved colour (like Full Size / Travel Size) stay as text buttons, which is expected.