Only one item added to cart when selecting multiple options

I have been using the WooCommerce Product Builder plugin for several years without any issues. However, recently I noticed a problem with the add-to-cart functionality.

Issue description:
When customers select multiple items/options in the product builder and try to add them to the cart, only one item is added instead of all selected items.

Steps to reproduce the issue:

Go to a product using Product Builder
Select multiple items/options
Click “Add to Cart”
Only one item is added to the cart

Expected behavior:
All selected items should be added to the cart.

Actual behavior:
Only one item is added, even though multiple items are selected.

Troubleshooting done:

I have deactivated and removed all other plugins to check for conflicts
The issue still persists even without other plugins

This issue is affecting my customers and preventing them from purchasing correctly.

Please help me identify the cause and provide a solution.

Thank you in advance.

Best regards,