I'm currently working on a shopify dev site and there's this one issue on the collections page in which one of the collections is not displaying the correct product count (Like the products total in collections dashboard is 56 but showing 49 in the frontend) and not displaying the products correctly (majority are correct but some are not.) I believe the site is using a app (plugin) called Product Filter & Search by BoostCommerce. As when I change the template for collections, the products are all showing correctly. I cannot send the site link as It its on maintenance mode.
I'm Ann, from the team here at Shopify :)
In this case, it's definitely hard to see for sure what might be happening here- however, from the sounds of things, it does sound like it might be an issue with the app directly. In a case like this, it's best to reach out to the app developers in order to have them take a look. You can see the contact information for app developers on their app pages directly.
Alternatively, it could be something else in the current theme that is causing this. In that case, you can check out the theme and who supports it (Shopify or third party developer) and then reach out directly. Check out this page in our Shopify Manual to learn more. If you're having trouble figuring out who supports this theme, let me know what theme you are using and I can take a look.
I hope this helps! If you have any more questions or concerns feel free to reach out to us on this thread :)
Have a great one,