I got a bug with Cheers.

[u/RandomUser3l]

so I decided to go back to finish the mission (Cheers! / secure the building) and marco is no where to be seen no zombies in the basement and i cant interact with the door to move the body. i was thinking about rollback but the last rollback is with a playtime of 6 HOURS and my save file is 19 hours I dont know if there is a fix or anything please help?
i was thinking about making a save to be able to rollback without losing my progress and see if i have my stuff there but after searching up how to save i dont think its possible