Hello,
I see that you have a customize HTML structure on that page http://prntscr.com/uva12g , not the default one http://prntscr.com/uva1wz And this is the reason of the problem. We found that Imagify plugin causes the mentioned problem, actually this option that you enabled http://prntscr.com/uva67z
I have disabled using of the picture tag and the swatches image works fine.
Regards