New testimonial not showing on gallery page carousel slider

Hi, I have just added a new testimonial as an image to a gallery page (testimonial carousel slider), however it doesn't seem to be picking up this new 'image'. Is there somewhere where I should specify the number of images on a gallery page?

Thank you!

Can you share link to page where you use testimonial? We can check easier.

Also, you can use Summary Block to add testimonial.

Or use this testimonial slider plugin.