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 current, still-open 24-hour bin for today, the number keeps climbing until midnight rollover, so it should be read as "so far today" rather than a finished daily total. On an access port serving a multi-dwelling unit, a count of 1,436 over today so far 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.