Xshippingpro matches rule categories with cart categories one by one during checkout. So it never permit a category that are not listed under rule categories. But often one product could be assigned to more than categories. To work properly, you should enter all categories of a product to the rule categories list although it is not comfortable to enter each category for a single products.
Multi-Categories Rule can help in this case. You don’t need to put every categories of a product to the rule category list. Instead you can select only one of them, and choose Multi-Categories Rule to “Any” that will do affect same thing as entering all categories to rule category list.
For example, you have a product which was assigned to category A, Category B and Category C. By default, you will have to select category A, Category B and Category C under xshippingpro category rule. But if you choose Multi-Categories Rule to “Any“, then it is enough to choose category A only under xshippingpro category rule to work properly. It will be same thing as choosing category A, Category B and Category C.
Multi-Categories Rule will help to save your time a bit.