This counter tracks frames received where the flow ID did not match any valid, configured flow descriptor on the unit. This indicates frames arriving with a flow identifier the receiver doesn't recognize -- commonly caused by a flow being reconfigured or removed on the transmit side without a corresponding update on this receiver, or by cross-talk from an unrelated carrier sharing the same frequency plan. If a network operator reprovisions a flow descriptor at the hub without pushing the matching update to this remote unit, every frame using the old flow ID will register here until the configurations are resynchronized.