Mot_slewrate not applied when turning

I’m on 4.2.3 with differential thrust (throttle left/throttleright)and using a reduced slewrate (Mot_slewrate) to soften motor acceleration as i have 20" air props. I notice the slewrate value does work for fwd/rev drive but when i give roll input the motors accelerate at normal rate and the parameter is not applied. Is this a simple miss or was it intentional? I realise it will dampen the tuning for auto modes etc.