I recently updated to XCode 4.6 and I'm having problems re-symbolicating a crash log. I was able to do it before for this same project. I normally do it by dragging the file to Organizer -> Devices - > Device Logs.
My project has most of its code inside a library that is linked to the main project and for which the source code is part of the workspace.
I checked another project and it happens to it too, so it seems something related to XCode 4.6.
I wonder if this is also happening to someone else on the community. I'll keep digging into it and update this post if I find something.
Thanks!