First event not getting recovered in Queue


I am testing the messages getting recovered in Queue, when the trigger is suspended.

Flow is a message will be posted to Topic, from which it will be routed to Queue based on filter join.

I am posting 3 messages from IS to Topic with trigger being suspended, 3 messages are being recovered in the Queue.

When the source system is posting 3 messages to Topic with trigger being suspended, only 2 messages are being recovered. First message is not getting recovered. While I could see that 3 messages are pushed into the Queue by source in ‘Pushed’ count.

Not able to figure out where might be the issue.

Please suggest solution.