Stereo cameras only partially updating animated scene

I’ve modified one of the ThreeJS examples by mounting a stereo effect camera to the model. However, when viewing the scene from the stereo cameras, the model geometry does not appear to be updating according to its animation loops (See attached photo). Interestingly, the background and the overlaid skeleton helper appear to be updating. It’s just the surface geometry that seems to be stuck in the ‘idle’ pose. Can anyone give me an explanation for this behavior and/or a recommendation for how to fix it so that the geometry is properly updated in the stereo camera views?