You are using two coils at 90 degrees to to create a spinning magnetic flux so that your magnet (needle) aligns with it yes?

I think the problem is largely the way the flux density from each air cored coil is almost constant (close to and across) the face of each coil. Outside the "projected" tube formed by the coil, the flux varies with distance at a much steeper rate and round about halfway between the two quadrature coils the change in flux per angle turned will be quite linear. I'll try and make a picture that helps. Bear with me.