Recently I made a new post in the Plugin Topics forum section.
Then I was checking back and notice that the ‘new/recently updated drop down list did not show my post but instead shows older posts which do not appear to have been recently updated or new.
So seems to be a possible bug?
Actually, I think it could just be that MY new posts do not appear in the drop down list to me unless they have been updated by someone else?
Correct. The QuickLinks, new post handling etc., is all personally and dynamically generated for the current user. The same way that they will not be shown topics in forums they can not view.