Even I set the aspect ratio to 2.35:1, the shooting still results a aspect of 4:1. The problem only appears when shooting 60fps videos.
Due to extra line skipping in high fps mode, the resulting pixel aspect ratio is not 1:1. Instead it is 3:5. 3/5 * 4/1 = 2.4. Did you actually look at the resulting footage? Notice anything strange about it?