In Civil 3D 2013 there is a new bug that I found while trying to set my plan & profile sheet template. In order to use the plan production tools the viewports need to be defined as “plan” & “profile”. If you select the viewport and access it’s properties you will find the Viewport Type Section where you can define which type you want the viewport to be. By default the type is “undefined”.
The issue arises when you need to change that viewport type. When you change it to anything else but the undefined, it reverts back to undefined. Now this presents a real issue since you cannot use the plan production tools without the viewports set the right way.
The workaround as discovered by Matt Kolberg is to change the new introduced sysvar called PROPERTYPREVIEW from on to off.