Hello,
This is an UE related issue.
On every startup UE generates a file ( ProjectWerewulf_PCD3D_SM6.upipelinecache ), and sometimes the engine failes to generate it correctly.
To solve it go to "User/Appdata/Local/ProjectWerewulf" folder, and delete "ProjectWerewulf_PCD3D_SM6.upipelinecache" file, then restart the game.