I have two monitors of the same make and model.  They are standard and not ultrawide nor are they 4k.  Windows identifies the right-side monitor as Monitor 1 and the left-side monitor as Monitor 2.  Nvidia's Control Panel identifies them the same....right-side is 1, left-side is 2.  Every time I launch Space Marine 2, it open on the left monitor (2).  In the Video settings, the target monitor is Monitor 1.  If I change it to Monitor 2, the game will switch to the right-hand side where I need it.  If I leave the game and come back, it again opens on Monitor 2 (left side).  The game is clearly mis-identifying Monitor 1 and 2.