Testimonials Not Displaying Randomly on Page Refresh

Hello,

My site has WordPress 4.8.1 running Highend 3.4 theme.

I am using the Testimonial widget in the sidebar with the setting ‘Order testimonials by Random.’ (screenshot attached) However, when I reload the page or load a new page, I keep seeing the same testimonial. I have 26 testimonials so I should be seeing a different testimonial every time I load the page.

Can you please advise?

Thanks.