This read-only Counter64 counts the number of times this PM instance timed out waiting for hosts to reply with membership reports after a query. Admins use this to catch unresponsive or powered-off multicast receivers before the switch prunes them from the group and a subscriber notices the stream stop; because it is drawn from the most recently completed short-interval historical bin, it is a closed record of the interval right before the current one, useful for checking whether a problem seen right now had already started in the previous window. On an uplink toward the multicast-enabled core router, a count of 298 over the last completed collection window is the kind of number an admin would trend against the join/leave rate on the same port to judge whether it's normal channel-surfing or an anomaly worth a closer look.