I have the same problem on http://www.nomadi.hr/friske-vijesti-o-putovanjima-s-nomadima/
<img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" style="background:url('') no-repeat center center;-webkit-background-size:cover;-moz-background-size:cover;-o-background-size:cover;background-size:cover;" class=" wp-post-image nelioefi" alt="" draggable="false">
i tried to set external image manually and it works
EDIT: didn’t have older versions of the plugin just installed the latest
i have rather simple css workaround i use
in my case select has id pa_adhesive_tape
so i just made 1st child there not display with css
select#pa_adhesive_tape option:first-child{display: none;}
