k here’s some other stuff you should try then :
1 - bash the ctrl/alt/shift keys on both the left and right of your keyboard.
2 - do you have another piece of hardware that has ctrl/alt/shift keys that you haven’t bashed? (like a cintiq? or maybe you have ctrl/alt/shift bound to special mouse buttons? or you have more than one keyboard plugged in? )
3 - you should then try closing ALL adobe apps, including creative cloud. i personally only use PS:CS6, so it could be there are more adobe apps at fault possibly and i never found that out.
4 - then try closing ALL apps except unreal.