Professional :: 3D Rotation For Symbol About Y Axis Using Pivot Point

I am trying to rotate a symbol about the y-axis, 45 degrees one direction, then back to center, then 45 degrees the other direction. Seems like a relatively simple task, except here is what happens.

Here is the object with no rotation:
Here is the object rotated exactly 45 degrees:
And here is the object rotated exactly -45 degrees:

I need the object to rotate the same as it did the first time but in reverse, otherwise "45" and "-45" are generally worthless numbers to refer to. Is it something to do with the pivot point? I made sure the registration point was in the center when I created the symbol. It doesn't seem to be pivoting the object around the center though. How do I rotate about the y-axis using a pivot point that is actually in the center and gives the same (but opposite) effect when rotating it one way versus the other?