With the new navigation, the filter "show" and the tabs "New" and "Need answer" seem to behave unpredictable.
When selecting the tab "Need answer", the "show" filter seems to be standard on "Need answer". In this view, the least questions are shown. It seems a little weird to have both a tab "Need answer" and a filter "need answer" which don't seem to be linked somehow, but I can live with it.
When changing "Show" to "All", more questions are shown. Since the collection "Questions that need answers, that need answers" and the collection "All questions that need answers" are the same, I expected this to show all questions, but this is not the case. It does show more questions that the "Need answers" filter option, but curiously not all questions.
When clicking the "New" tab, filter is automatically set to "all" and cannot be changed. There are somehow questions here that do not show with "Tab: Need Answers" / "Show: All". There does not seem to be an obvious pattern in the questions that are only shown in this configuration. There are questions without answers, with answers and with accepted answers.
This behaviour seems wrong to me. Either the tabs or the filter options should be renamed to closer represent what they do, or the queries that are run should be changed.
An example can be seen when browsing the ajax-success tag on StackOverflow. I went through the entire "Tab: Need Answers/ Show: All" view and edited the tags to be something more sensible. I was notified today that there were still questions with that tag. They are only visible under "Tab: New/ Show: All". I'll leave them there for the time being so you can take a look at them, and possibly figure out what is happening.