Sales Order cant be released if on hand quantity is partially blocked in locator. Why?

I created a Sales Order for item XYZ for 10 pcs. I created on hand quantity with 10 pcs with material status Active. Sales order release was possible ⇒ Pick slip was generated.

I re created the example with same item and qty and blocked 2 from the 10 pcs so they would not be availalble for ATP or reservations. I seperated the 2pcs in a different LPN but with same lot number as the 8 active pcs. Both LPNs remain in the same locator. Sales Order delivery tolerance is 25% so the Sales Order should be released. ⇒ Sales order release was not possible

I moved the LPN with the 2 blocked pcs to another locator ⇒ Sales order release was possible, pick slip was generated