In the Log Activity tab, use search filters (like Event ID and type (could be custom CEP) and perform a search and make sure that the result you see is what you want it to be in the report. Once you get the desired output, you can save the search and create report out of this saved search.
How to create a saved search?
https://www.ibm.com/docs/en/qsip/7.5?topic=searches-saving-search-criteria
#QRadar#Support#SupportMigration