This counter counts prefix consistency queries this checker sent but for which no actual consistency check was performed, due to some internal error or resource failure. A nonzero and growing value here is itself a health signal about the checker, independent of FIB correctness, meaning the consistency-checking subsystem is failing to do its job for some queries and real inconsistencies could go undetected. An admin seeing this counter climb during a period of high CPU load would suspect the consistency checker is being starved of resources, and would want to investigate overall router load rather than assume the FIB itself is fine.