Don’t know if either or both of you got a fix on this, but this is how I managed it. Had a white t-shirt, with swatch that didn’t show up. Easy enough to fix that, but it left me with a white checkbox that wouldn’t show up. I got rid of that by changing the border to transparent in the second item below. This works for me. Change the #cc0000 to something else if you want some color other than pink for the glow around the selected items. And, of course, add this to your theme stylesheet, rather than editing the plugin files.
.tawcvs-swatches .swatch {
border: 1px solid !important;
border-color: #999999 !important;
color: #cc0000 !important;
opacity: 1 !important;
}
.tawcvs-swatches .swatch-color.selected:before {
border: solid transparent !important;
}
