controller sensitivity glitch

This sounds like it's a problem with the controller, if it's an old controller or it's been beaten up a bit while you've had it. If you've tried with different controllers, it could just be that your Xbox is getting old. How long have you had your model?

Turns out that the glitch is that the gamma and sensitivity settings mysteriously reset themselves to 0%.

you can also turn down the sensitivity of the aiming in the controller options

X sensitivity controls how fast you look left and right

Y sensitivity controls how fast you look up and down

I've never had any issues with sensitivity either with the stock controller or with the elite controller which I now use, in all fairness I've never had sensitivity issues with my PS4 controller either but it would also be fair to say that as a primary
PC gamer I'm used to ultra sensitive control methods!

Hello Ben!

We understand the issue being experienced!

A suggestion we can provide, would be to reset the console to factory settings.

To be more specific, perform a soft factory reset.

This process found on our How to reset your console to factory defaults on Xbox One article will guide you through
this.

Be sure to find Reset and Keep My Games and Apps.

Let us know if this works!