I get an event with that exact start time. I know I can do this with a more complex query - but am I just mis-understanding how whereDate is supposed to work?
Are you doing something like foreach($events as $event) and checking? Or you can also do $events->count() to see the total there.
I played around with this in Tinker and it seemed to work well for me. The trick was that if ->paginate() vs ->get(), Tinker just shows a pagination object. You have to spin through that object to get the results.