Huge gap in masonry grid.

[JGSFLA]

I am using Splide with a snippet I created so programmatically it gets all images attached to a post, inside individual posts it works fine but once I retrieve posts via Ajax Load More (using a callback function so the splide carousels load again individually) and display such posts in a masonry grid, all the posts that have the Splide snippet create a huge horizontal gap. The gap disappears when I resize the window.
This does not happen with several other sliders I tested but Splide offers all the features I need, the other don't.

Any idea as to why the gap and why it gets corrected once the window is resized?

I tried to do html {overflow-y: scroll;} and body {overflow-y: scroll;} as suggested in masonry support and documents but it had no effect...