Just spent a few hours debugging this little delightful side effect of using local3DToGlobal on a DisplayObject that I’d set it’s matrix3D property to null (to remove the effect of blurry graphics after 2.5D rotations and z translations).
Beware: using local3DToGlobal on a DisplayObject that doesn’t have a matrix3D property will result in that DisplayObject having a new matrix3D property created on it’s behalf. Not sure that’s entirely logical, but it’s what the boffins at Adobe thought was best… grrrrrrrr!