Hi Smikey, we appreciate your patience. Actually we tested the feature in our environment and didn’t get any problem. We want to troubleshoot your problem and need some co-operation from you. First, let me know about your hosting server. Because some WordPress optimized hosting server by default disable the order by rand feature. In this case order by random will not work. For example if you use WP Engine hosting then you need to enable order by rand from admin panel. Otherwise it will not work in the query.

Second please provide a detail screenshot of your option set. We will try our best to figure out the problem. Thank you.