If a message doesnt "sit" on a queue will APM even see it.
Can someone explain how this actually works.
Using MQ Agent to monitor websphere MQ v8
Yes, the MQ agent will "see"all messages going through a queue regardless of how long time a message sits in a queue. The agent is using internal MQ monitoring queues where MQ is configured to extract monitoring data and put in special purpose monitoring queues that the MQ Agent reads from. Hence, the guarantee that the MQ agent "sees" all messages is by design from MQ itself.