Slider and lightbox pictures not loading till I move mouse

this just started in the last week and I cant figure out why. when I go to one of my site pages that has a slider or lightbox image on it, the images will not load if I don’t move the mouse at all. All Browsers.

examples, go here, click the link and don’t touch you mouse at all. the pictures will not load, move your mouse over the page and the pictures will load.
Artistic Images – Online Photo Gallery

Landscapes – Artistic Images

All fixed it was WP Rocket and “Delay JavaScript execution” was checked.