Issue
After the campaign is run for deleting leads, the result tab shows as "No activities found".
Solution
Whenever a lead is deleted using a Smart Campaign, the results tab will not show the list of leads that got deleted as they are not available in the database anymore. However, with the help of "Run History" tab you will be able to see the number of the leads that got deleted. Once the campaign is run and the "Delete Person" flow step is executed, the lead will be deleted immediately from the Marketo database.