Masonry is a JavaScript grid layout library. It works by placing elements in optimal position based on available vertical space, sort of like a mason fitting stones in a wall. You’ve probably seen it in use all over the Internet.

I had to use imagesLoaded to solve my problem

jquery.imagesloaded
//cdnjs.cloudflare.com/ajax/libs/jquery.imagesloaded/3.0.4/jquery.imagesloaded.min.js

$('.gallery-masonry').imagesLoaded( function(){
 $('.gallery-masonry').masonry({
 itemSelector: '.item',
 isAnimated: true,
 isFitWidth: true
 });
 });