Manipulating Navigation Mid-Game
Using the AIGraph Element, you can enable or disable entire Navigation Segments. Link the Element to the Nav segment either by opening the Graph Unit list with the button or the M hotkey, or holding SPACEBAR and clicking on the segment.
With the Operation setting you can either allow or forbid access to the linked segments, and even forbid access only for certain AI types.
Door Blockers & NavObstacle Element
Another way to prevent the AI from reaching certain areas is with the use of Door Blockers. Instead of blocking the entire segment, door blockers block only the parts of the mesh they collide with.
They are most commonly used to block doors, hence the name, but they can be used in many other ways, for example vehicles that roll-in at a later point in the heist like SWAT trucks.
You can find door blockers by looking for them in the Spawn Menu, they are usually colored Pink. Door blockers have to be enabled and disabled using the NavObstacle Element. Link the Element to the Door Blocker either by opening the Obstacle list with the button or the M hotkey, or holding SPACEBAR and clicking on the Unit. In the Operation select “Add” to block the navigation and an additional NavObstacle Element with the “Remove” Operation to make the navigation accessible again.