A while back we noticed MICS MQSeries component started reporting TAACOUNT=0 always (should only occur for long-running task/even instances).
Further investigation with IBM determined that WTASFLAG is/was considered to be an IBM-internal flag unknowingly (WMQ v7 RSU1406 maintenance) without concern that documented condition WTASAEOT is used by MICS to identify an end-of-task condition (event termination).
Since contacting IBM support, an IBM APAR PI27817 (v8) and corresponding v7 APAR PI27511 are forthcoming to re-instate WTASAEOT.
Recommend MICS MQSeries licensed clients track these IBM APARs to get them implemented.
In the meantime, consider using TAARECCT (always a value of 1) with computing average-type metrics, where otherwise TAACOUNT would be used.
Regards,
Scott Barry
SBBWorks, Inc.