Resets main product’s price to 0

When plugin is activated it resets the main product’s price to 0 when added to cart (even if upsell popup doesn’t appear on this product page).
And if upsell products are set for the main product, and upsell popup appears – it adds upsell product with correct price to the cart, but main product is added with same 0$ price to the cart. It also breaks product add-ons, since they are not being added to cart at all.

Wordpress ver. 5.3
Woocommerce 3.8
Woocommerce Multilingual 4.7.4
YITH WooCommerce Product Add-ons Premium 1.5.23