I have currently some troubles with the "client" block. it seems to not display more than 4 elements even if I have 5 or 6 clients in the backend. Also, if I add a second "client" block on the same page, no element is displayed on the page except the section title.
Client block is based on Owl Carousel. Is a image carousel block, that means that you have to slide right or left the carousel to show you images if your images are more than 4.
If you want you can enable autoplay to the carousel to show all images with auto slide. I can show you how to do it if you want.
Client carousel needs a unique id to work properly. So with the current implementation you can use it only once in your page.