Hi Steve,
We have never shown the calendar navigation on the post detail page. I think we did have a reason for that at one point but for the life of me I can't think of what it is or was or why we couldn't.
Therefore, I just now implemented a fix for this by adding a new setting to show the calendar on detail view.
So this will be fixed in the next release of mojoPortal and the fix will be in our source code repository soon.
Thanks,
Joe