Hi,
I am not sure what exactly you are looking for, maybe the reverse of the filter operators?
Because this right now works correctly, it does exactly what it should. If you flip the operators for the start/end dates, then it will show basically all ongoing events.
..or you can change the filed logic to OR, and then it will show events that either start after the date, or end before the date.
I recommend experimenting with these, one configuration will give you the expected results, I am sure.