This scenario is really common when we create rule that works on regular products and subscription products.

When a cart includes both a subscription product (which uses its own dedicated shipping methods) and a regular product, and our HideShip customization hides the subscription item, Shopify still verifies shipping eligibility for every item in the cart. It looks for at least one shipping method that applies to all products. If any product has no available shipping rate, or if there is no shipping method that works for every item simultaneously, Shopify treats the order as undeliverable and hides all shipping options.

 Subscription items have unique shipping methods; hiding them does not bypass Shopify’s validation.

If no common shipping rate exists or one item lacks rates entirely—Shopify removes all shipping methods.