Okay, we're getting closer. I think you're right, the query only seems to be going for certain payment status. Here's what happened when I ran your query:

324 total results
First order at: 12:01:24 AM

When I look at just today's results, using the correct timestamp in the URL:

11 results
First order at: 12:44:53 AM

However I know it's more than 11 orders here. It looks like they are all "payment received" as well. Hope this helps.