Random not working

Hello,

I have a post grid displaying alumni profiles on the front page of my staging site, and set to Order By: Random. However, all I get are the same two profiles, in the same order, all the time. I've done hard refreshes, opened new incognito windows, opened different browsers: same profiles, in same order.

How do I get a random selection of posts on each hard refresh?

http://coebioeng.staging.wpengine.com/

Post type: post
Advanced filters: taxonomy, order
Taxonomy: categories - Profiles
Operator: IN
Order By: Random