Xcode 4 Instruments doesn't show source lines

Question

I\'ve just started playing with Xcode 4, and found that, no matter how I setup debugging symbols in the project, Instruments refuses to display source lines for stack trace item

Answer 1

It just started working; no rhyme or reason.

I have spent the last half-hour trying to get it to fail again, in the hope of providing a more useful answer here, but I can't, even after recreating the skeleton OpenGL program from scratch, retracing all of my steps.

I did open the symbolicatecrash script in emacs (It has been implicated elsewhere, wrt this kind of problem), and it started working after I did this. But at no point did I change or save it.

It's a mystery.