Usually when the cart label is missing from the cart page or order, it's because:
- theme's cart does not support line-item properties. Pre-order Now uses line-item properties to add the cart label to orders.
- shopper added the pre-order product to cart via a quick shop / quick buy popup. Pre-order Now is not yet compatible with quick shops / quick buy popups.
AJAX / pop-up carts often do not support line-item properties.
We recommend reaching out to your theme developer to see if their cart is compatible with line-item properties and, if not, can make their cart compatible with line item properties.
Shopify has details on this feature here which you can pass along to your theme developer: https://help.shopify.com/themes/customization/products/features/get-customization-information-for-products
If your cart does support line-item properties and yet the cart labels aren't appearing, please contact support, and we'll be happy to investigate.