The user group overrides will show the dates that have been overridden, but any dates that are left to the default, they are not shown in the "view all submissions" page.
In simple situations where you are only overriding users, or only overriding groups, you can infer the information from the non-overridden users (not ideal). When you have a combination of group and user overrides it becomes impossible to determine when these due dates fall.

I've included a screen shot which shows the problem.