Ah dang it, I forgot, your weapon must be down as well for it to be reproduced.

I think they made it where you aren't able to do that. I read in the in-game field manual that, due to the Geneva convention, soldiers aren't aloud to wear enemy uniforms.

I think I know what you're going through, I had this issue as well. Here is what you do, go to your Arma 3 folder and right click arma3.exe then click properties. Click the compatibility tab, then look for "Disable display scaling on high DPI settings" and then click the check box next to it. Hit Apply and then OK then try to run the game.