A network engineer configures OSPFv2 on a distribution switch. The LAN segment facing end-user workstations should still advertise its subnet into OSPF, but no OSPF adjacency should ever form on that segment. Meanwhile, the point-to-point link to the core router must form a full adjacency. After applying 'passive-interface default' under the OSPF process, the engineer notices the core adjacency is stuck in INIT and never reaches FULL. What is the correct action to restore the core adjacency while keeping the user LAN passive?