From issue email:

I am modifying your cube_test example. Instead of keeping the end effector outside of the cube, I'd like to keep it inside. Yet when I do this, it works fine if you move straight along an axis however you end up going right through the corners of the cube. After a bunch of tests, it appears that the falcon cannot exert a strong force along 2 axes at the same time. Do you know if this is true? any other possible suggestions?