This counts TED probes dispatched by the local entity that failed to locate a crypto endpoint, per its description, again noted as unaffected by CLI operations. A rising value here specifically (as opposed to just probes sent) means discovery attempts are failing to find a live peer at the far end, which would explain traffic destined for a particular remote subnet never getting encrypted or delivered. An admin seeing this counter climb for traffic to a specific new subnet would suspect that subnet's owning router either isn't configured for TED or is unreachable.