Hi Harry,
Let me know if I've misinterpreted anything, but here's what I think is going on:
From your first screenshot it looks like you're trying to get at New Issues in a file through the Measures page. As you've realized, that's not going to work. The code viewer always includes all issues, regardless of context, and the measure value tells you how many of them are new.
You've also tried to get to this via the issues page, and what your screenshot there shows that all issues are in the leak period. That's what the first 2 parts of that composite screenshot show. The 3rd part of that composite seems to again come from the Measures page which, again, is going to show you the count of new issues, but not narrow the display (although we've just established that all your issues are in the leak period so even if there were filtering, all issues would still be shown).
Now... let's get to how to do what you want. For issues, always stick to the issues page. Yes, some issue-related metrics are available in the Measures page, and if you want to see distributions across files this is useful. But if you want to see issues then use the issues page. For this you would filter by:
Creation date, and then use the File facet to further narrow your result set. Unfortunately, there's no input in this facet to allow you to select a specific file that's not already in the list. I think that's an oversight, and if we don't already have a ticket in the backlog for it, I'll create one.
Ann