scheduled posts not publishing

I’m experiencing an odd issue and can’t seem to find any clear cut documentation on this, at least documentation I can understand. Right now I’m running 2.6.1 and when I schedule a post to display at a specific time, it does not publish.

I’ve verified that my time zone settings are correct but what’s happening is that if a post is scheduled to post at 12:00pm (I started writting this at 11:50) for example, the Manage > Posts listing will say it’s scheduled to post in 10 minutes from now. However, when the time comes and goes, it says the post will publish in however many minutes or hours have passed since the publish date. For example, right now it’s telling me the post will publish in 10 minutes. So it’s taking the time and reversing it somehow.

I was previously using MT, do I need a cron job pointing to a specific PHP file?

Thanks in advance!