Why am I not able to see some events missing in the events page?
The Events page displays only top 10000 most recent events from the Events table. So if you are not able to find the events in the Events page, there is a possibility that those events might have not been in the top 10000 most recently occurred.
In order to maintain consistency and ensure optimal performance. OpManager performs an operation called Event table Clean up .You can read more about events table cleanup here. During events cleanup, a new event table will be created and the new events will be populated in it. If the previous Events table is older than the user defined value for the 'Recent Events will be maintained for the last' parameter, the table will be dropped. Consequentially, the records in the table will also be deleted and hence you will not be able to see those events in the Events page.
If you wish to hold the dat a in the Events table for a longer period of time, you can increase the value for the 'Recent Events will be maintained for the last' parameter under Settings -> Basic Settings -> Database Settings. However, note that increasing the value will affect the performance of OpManager.