Featured Images Not Loading On Slider and Home Page

The slider and home page post are not showing the featured images. When I make a new post I select featured posts for the image to be displayed right? Well that’s checked and None of the images are showing up in the slider or in the post section underneath. I’m not sure what the problem is exactly.

My first time using this theme. I Need some help please, this is the last step for my page. Thanks.