Dawn - "show second image on hover" only works on some images

[noxane-ecom]

When I hover my cursor on my products only some of the products will show the second image and the remaining of the products just zoom in on the first image. What can cause this error? 

I uploaded a code manually to show "variants as separate products"

I first added "card-variant. liquid" under snippets and then I edited " main-collection-product-grid". 

Thank you for your help.

[noxane-ecom]

Solved!