O365 event not collect each events

Hi All

 Base my revious discuss about O365  file rotation interval . I change it to 600 (10 mins) to fast check testing event.

then I create O365 policy....each policy set monitor All events.

Then I test common testion cenarios like mail move/delete , user delegation(send as / send on behalf)  in 10 mins.

But I find these testing events ....sometimes could be receive...sometimes not receive (I have wait 1 hours). 

Who has use O365 module to monitor Exchange Online ??