Increasing the mouse Input Scale beyond 4 causes an unwanted camera bounce back

The video of the settings & results before/after is here: - YouTube

My mouse input works smoothly in the normal range. But I’d like to speed it up… so I increased the mouse Input Scale to 5, which is about the speed that fits the game imho.

It kind-of works as planned, the speed is right now… but if I move the mouse quickly there is an immediate camera bounceback (especially in yaw, less so in pitch), like the camera is hitting an invisible wall. After this one-time bounce, it rotates and resolves as intended, but in the wrong direction as you may guess.

It seems that increasing the mouse Input Scale settings in the PlayerController… beyond a value of about 4… causes this effect. Pushing the Pitch & Yaw Input Scale values to 100… causes the effect even more noticeably. It happens every time I move the mouse quickly (slowly is fine, unless the scale is set very high).

Thanks for your help, David

Is this a bug, or am I missing a setting somewhere?