The way I've always understood the central delivery block functionality (XD05 / VD05) to work is that when the delivery block is set, any subsquent orders for that customer would have that delivery block automatically set. This is done through configuration (SPRO -> Logisitics Execution -> Shipping -> Deliveries -> Define Reasons for Blocking in Shipping)
I have two business users that say that it didn't used to work like this. They have explained to me that they've seen the system configured to allow them to set a central delivery block, but the block would not copy down to the sales order. Orders would be blocked from delivery until they remove the central delivery block on the customer master.
Have any of you seen this before? Was this a standard feature at one point, or did you have to build something custom?