I'm using a non-polarizing beamsplitter cube in an experiment, but it's behaving in an unexpected way. I expected that, if a laser beam enters the cube from one side, ~50% of the beam passes through the cube in the same direction, while ~50% of the beam is reflected and exits the cube at a 90-degree angle. So, one beam entering the cube and two beams exiting the cube. Instead, the beam seems to exit the cube in all 4 directions: passing through, exiting left, exiting right, and even being reflected back to the source. Is this expected behavior? What is causing it? Thanks!