Have you tried removing the 'was delivered' or 'was sent' filter to see if that helps. It might be getting confused with all those options. I would normally do was was sent and not opened.
Also, have you checked how many of your leads didn't open then email?
I would try building a smart list with was sent email and not opened email. That should get you a list of those that were sent the email, but didn't open it. The extra criteria may cause them to not show up on the list as they have to have done everything you listed.
I would create a new email send campaign as the program is likely completed already so won't cause them to go through more steps.
Doing something based on just opens is risky. What about those people that did open, but didn’t have images enabled (which is the default in Outlook)? Or those people that didn’t open themselves, but was opened by a link scanner?