Can't Add a Extension to be Executed by session handling rule for checking invalid session

Hi, First off just wanted to say that you guys have been doing a great job with Burp, it pretty much covers 85 - 95% of my daily web app pentesting needs with the core functionalities. So my problem is exactly as stated in the title. I have an extension loaded with ISessionHandlingAction implemented, and the getActionName method returning "Refresh Midway Session". I have defined a session handling rule for checking if a session is invalid, using Burp's built-in rule, and at the very bottom of the "Session handling action editor" window, I checked the "After running the macro, invoke a Burp extension action handler", and specified my extension's action handler in the dropdown box. However, when I close the dialogue box, and reopens, the action handler is deselected. Any help with this matter would be appreciated.