After running a Smart Campaign to delete some records, you don't see any deletion activities in the Results tab. It appears the campaign did not run.
If you ran a Smart Campaign to delete records and the only flow action is to 'Delete Person', you will not see any activities in the campaign results as these activities would be associated to the deleted records. This would lead to the impression that the campaign did not run, even when it did.
In order to check the status of the campaign or if the records were deleted, you can check the 'Run History' of the campaign to see if it has one of the following statuses:
"Completed (number of people qualified)"
"Running campaign - executing flow"
If the campaign is still running, you can also check the Campaign Queue to see if the campaign is still in the queue.