Can't seem to get Post Snippet working anymore

I use this plugin to help navigate in between posts by using the following code:

$links = siblings();

 $previous = '<span class="prev"><a href="%s"><i class="icon-chevron-left icon-2"></i></a></span>';
 echo sprintf($previous, $links['before']);

 $next = '<span class="next"><a href="%s"><i class="icon-chevron-right icon-2"></i></a></span>';
 echo sprintf($next, $links['after']);

I’ve done this site a long time ago and the recent updates I’ve made don’t seem to work with Post snippets. I do change the shortcode in my updates accordingly. My updates just don’t seem to register as sibling pages. I’m sure it’s a silly mistake but I’ve looking quite a bit and can’t seem to figure it out.

You can view the site at https://www.linavandal.com/
Post snippets is used once you click on a thumbnail to generate the little arrows to navigate in between collections. I have 3 collections that just get skipped altogether by the navigation (and these are updates from after I launched the site which leads me to think I just forgot a simple step). I don’t think I’ve updated anything since then (either WP or the plugin)

Thank you for your help!

https://www.ads-software.com/plugins/post-snippets/