Unfortunately, or fortunately, no member of my office's staff—not even those who have been there for 15 years—can remember a case where information was not provided, and I can't either. That has never happened.
I can envision certain cases where that could happen, but it would be for reasons of operational security—for instance, during missions abroad such as those in Libya or in Kandahar, which has ended. Otherwise, on Canadian soil, I cannot recall a single case. It has never happened.