Oh my god same. Until I found this comment I couldn't even figure out how to trigger 3D mode at all, I was just staring at the 2D plan in utmost frustration clicking "3D plan image" over and over. This is a great product hampered by a not great UI right now.
I'm pretty sure that "3d plan image" are the orthographic top-down renders. To me they look very 2d, but I guess technically they are 3d renders (that do everything in their power to not be 3d)