Setting expiry for a single post shows same date to all posts

Hey, I’m just a user of the plug-in, not affiliated with the author in any way but thought I’d throw my thoughts on the screen and see if they help you out:
1. Have you deactivated all other plug-ins to identify any conflicts?
2. Have you tried with the vanilla WP theme that comes with 3.8?
3. Did you set the time in Settings?

I use WP 3.6.1 at the moment (I have formalized Acceptance Testing procedures that all versions of WordPress have to pass and usually WP releases updates so fast I’m typically several versions behind. Frankly, it’s never been a problem for me from a security standpoint) and it works perfectly so I cannot speak to it’s compatibility with 3.8 but the above steps might help you at least begin to identify where the problem is living. 🙂

Cheers!