You need to run game on window mode otherwise the game will be frozen. For DCS you don't need specifically in window mode. If your screen is frozen then use alt+enter to switch b/w window and fullscreen mode.
The 2nd reason might be your active window is TrinusVR or any other if that is the case then just click on DCS window. So it becames the active window
TrinusVR don't run games in fullscreen what I know.