I always use the native featured image for archive pages and always works. As you didn't specify your URL, I cannot check your site to see your actual configuration. The same settings for changing the image order can be found at Layout: Excerpt / List / Tile / Mosaic / Full -> Tile layout -> Image preference order (if you use tiles to display your excerpts). Or, if you use magazine template you need to set the order of images at Templates -> Magazine in headlines or in excerpts.
Also, after changing thumbnail settings, may need to use a plugin like Force Regenerate Thumbnails
Not saying that any plugin or function you may added for dealing with images can interfere with the theme settings.