VCBS upsell popup crashes with Dizzain AJAX added_to_cart event

Hello,

I purchased and installed WooCommerce Boost Sales / VCBS on a WP Engine development website.

Development URL:
https://nsm2dev.wpenginepowered.com/product/nagham/

The upsell configuration is correct:
– Upsells are enabled.
– Hide on Single Product Page is disabled.
– WooCommerce cart redirect is disabled.
– AJAX Add to Cart is enabled.
– Show if Empty was enabled for testing.
– Nagham has manually configured upsell products.
– VCBS scripts and styles load successfully.

The product is successfully added to the cart, but the popup does not open.

The browser console shows:

Uncaught (in promise) TypeError:
Cannot read properties of undefined (reading ‘0’)

File:
modal.min.js

A diagnostic listener confirms that the WooCommerce added_to_cart event fires, but its arguments are missing:

cartHash: undefined
button: undefined

When I manually retrieve the WooCommerce cart fragments and trigger added_to_cart with the standard arguments:

[fragments, cart_hash, $button]

the VCBS popup opens correctly.

This confirms that the popup, product mappings and VCBS frontend assets work. The compatibility issue is that the Dizzain theme’s custom AJAX Add to Cart triggers added_to_cart without the button/cart arguments expected by VCBS.

Please provide a compatibility patch that either:

1. Makes VCBS modal.min.js safely handle an undefined button argument; or
2. Derives the product/button from the active WooCommerce form; or
3. Hooks VCBS into Dizzain’s successful Add to Cart event.

Please do not change the promotion or product pricing logic. VCBS is only being used to display an upsell product-selection popup.

Thank you.