I've seen several references to an issue in which imread fails silently when the wrong libs are used. It's working properly for me in release mode, but not in debug mode. I've triple-checked that my configuration is the same across the two with the exception of adding a "d" at the end of every lib's name, for "debug". So instead of including opencv_highgui248e.lib, I include opencv_highgui248d.lib. I'm using visual studio 2012, building for x64. My library path is C:\sdf3\opencv_2_4_8\build\x64\vc11\lib (though I've also tried vc12).
Any ideas what else I can try?