WP Network - Some sites send emails others do not.

I am having some REAL issues with this plugin. It used to be simple and reliable and now it is fancy and unreliable at best.

I am still having an issue where certain sites are not sending out emails and when I go to the dashboard > subscriptions > Sent emails nothing is listed. Also of note is that when the user publishes a new post they are immediately taken to a page that looks the html email that should be sent out. Clicking refresh then takes them back to the post as it should. Something seems broke and the trigger for the email is not being completed is my guess.

Is this a case where the database tables are not being created correctly?

Other sites in the network are fine.

What can I do to begin diagnosing and fixing this issue?