The question concerns an OSPF configuration where the interface does not come up as expected.

Common reasons for no OSPF adjacency or interface participation include:

Interfaces being passive (no adjacency formed)

Mismatched OSPF process IDs

Missing loopback interfaces (for router ID)

Layer-3 interfaces not associated with VRFs when VRFs are configured

Option D (a Layer-3 interface has not been associated with a VRF) is the root cause because in Aruba CX switches, when VRF is configured, all Layer-3 interfaces that participate in OSPF must be associated with the correct VRF instance to establish adjacency and participate correctly.

If an interface is not part of the VRF configured for OSPF, it will not appear in the OSPF interface list or form neighbors.