So I was resetting my mouse sensitivity settings after messing about with DPI settings in another game and discovered a possible bug.
Start up Battlefield 1, join an empty server to measure a 360 degree turn. ALT-TAB into Windows then go back into Battlefield, measure a 360 degree turn. They should be exactly the same but they are not and the difference cannot be put down to user error. The new sensitivity is faster. Only seems to effect Full screen mode.
Mouse: Zowie FK1
In game sens: 7%
Raw Input: On
Mouse mats: Asus Strix Glide Control, Everglide Titan, Steel Series 5l.
Happens in both Full screen and Windowed mode.
After further testing Sensitivity can increase or decrease sensitivity. It can also be change by the game stutter/freezing.
Can get it to do it with both Mouse Raw Input On and Off.
Mark C mouse fix applied.
Happens with capped and uncapped frame rate.
Uniform Soldier Aiming On/Off no effect.
Mouse is fine in other games.
Tried several different USB ports.
Changing the polling rate to 125mhz seems to fix the issue (so far).