BIC seems to have added a new failure mode when they redesigned the spark wheel. It used to be solid metal but is now a metal spiral wrapped around something else (plastic?). I've had the new version become jammed and unusable. I've also had the flint mysteriously vanish.
When operating correctly flint lighters work much better than piezo lighters at altitude. In fact I've never had a piezo lighter work above, say, 7k feet. I guess there's just not enough spark for whatever happens to the fuel:air mixture up there.
As a coda, matches aren't what they once were, so I feel better with a second BIC as backup rather than matches.