I have been using the woocommerce_add_cart_item_data filter to add custom product data to the cart and it was working great. On my dev site, I upgraded to woocommerce 3.0.1 and neither the product nor the custom data are added to the cart. Other products in my shop that do not have custom data can be added without issue. I have no indication that an error is happening. The page simply refreshes and the cart remains empty. Does this filter no longer work? What is the replacement?
Read more here: Woocommerce filters not working after upgrade to 3.0.x