Quality Presets constantly adjusting size

I have a monitor with a resolution of 2560x1400. When Insurgency: Sandstorm is set to full screen the Quality Preset buttons in the display options violently and constantly adjust.

https://imgur.com/a/FYCFiyq

This issue exists on the latest stable build of Insurgency: Sandstorm too.

When setting the resolution to 1920x1080 this issue stops occurring in the latest stable version and CTE.

last edited by hazzard993