If you’re experiencing invisible enemies and weapons in Warhammer 40, 000: Space Marine 2, don’t panic. There’s a solution to this bug.
Space Marine 2 – Invisible Enemies Bug Fix
I will get straight to the point. The culprit for this peculiar phenomenon might be caused by the low graphic settings. Even if the game worked fine for hours before things went invisible, try adjusting them once more. Change everything to “Medium”, set Render Resolution to “Performance” and restart your PC. Then open the game and see if it resolved the problem. A few people from this steam community thread mentioned this method worked for them.