There seems to be still no full support for PNG images. At start, eg. when the page is loaded, all images are visible and are laying on each other. Over the time all images are disapearing in the second loop and it is working correctly.
The workaround is quite simple, so why not using this in the next version anyway?

The workaround is a simple jquery script:

$(document).ready(function() {
  $('.fancy-slide ul li').css('display', 'none');
  $('.fancy-slide ul li:first').css('display', 'block');
});