Yes, actually at my job a co-worker just found exactly such a bug yesterday: Debug build zeroed out the variable and the release build didn’t. So the bug only occurred in the release build, but could not be reproduced on the debug build where the developers work on. So in the end he found it because of the different compiler flags used for debug vs release builds at our work place.
Yup, the “roar that matters” is the one people can hear when you quickly approach the speed limit in the city.