Why is my pre-order system not displaying for all out-of-stock variants?

[MaxCosta]

Hello to everyone,

To recap, I created a pre-order system with the app for the "La Vie en Rose" collection.

On the majority of products, everything works correctly and the pre-order button is displayed correctly.

However, on some references, like here: https://www.denaive.com/products/paire-boucles-bouton-galet-zoe-3000001?variant=47689389965640

The pre-order is not displayed because not all out-of-stock variants are visible. This makes the pre-order system impossible.

I'll let you know as soon as I've accepted your request to collaborate on the site.

Thanks in advance for your help,
Max COSTA