So somehow there's a bug that must have something to do with zeus, I've gotten it a few times, but only after toying around with zeus remote controlling AI. Afterwards, all characters, be they remote controlled or my own character will have greyscale vision when aimed down sights. Happens in missions too, but I have screenshots from in the BI Arsenal. Only happens when using SOG😛F weapons, curiously enough
​​​​​​​