gd_listings sort by random doesn't seem to work

Hi

I have created a list on my frontpage https://slipangsten.dk where I want to show 3 random featured listings. I use the following tag
[gd_listings post_type=”gd_place” sort_by=”random” title_tag=”h3″ layout=”gridview_onethird” post_limit=”3″ show_featured_only=”1″ view_all_link=”0″ category=”0″]

It doesn’t seem to work prober, it always show the same 3 listings. If I change from random to latest it shows a different sorting (as expected) – but the random isn’t random at all – it just show the same 3 all the time.

Did I misunderstand something or is it a bug?

Kind Regards
peter