Okay, I just found the strangest solution to this issue, but still can't get it consistent. If I move the path first, then undo, it works as expected.
This ONLY works if shift is held before the rotation click-drag. If you shift in the middle of a rotation-drag, it immediately changes to scaling instead of rotation snap mode.
Still irritating, but at least there is a workaround. I'd still like to know if there is a permanent solution to this issue...I guess maybe I use paths more than everyone else because no one is really asking this question and I've experienced this issue on different accounts, different computers...
Must be AE CC 2015 you're talkin' about. It has disabled features, lots of bugs and some bug workarounds that to the newcomer must seem like voodoo rites.
AE CC 2015 it most certainly is. It can be quite infuriating, I could not imagine the expectations of a newcomer dealing with even something as simple as this not working as expected.