Is the Dynamic NavMesh Broken in 4.1/4.1.1?

Unreal Engine 4 - Dynamic Navigation / Maze Solving - YouTube (UE4Beta/4.0.2)
As you can see in this video, The AI was running around a randomly generated maze spawned during run-time using the Dynamic NavMesh; It was also working in 4.0.2.

UE4 - Dynamic NavMesh Bug Report 4.1 - YouTube (UE4.1/4.1.1)
Now in 4.1 also in 4.1.1 It doesn’t work like it should as seen in this video. In the first part of the example you have an epic made floor tile 400x400 with a player start on it, located inside the dynamic navmesh the player spawns and is able to walk on it just fine. this floor tile was placed in editor.

When it switches over to the dynamic level gen, it’s just allowing to spawn from dynamic player start. (same project) You can see the player is trying to move around the level hence the top left of the view port changing from click for mouse cursor to Shift + F1 for mouse cursor. The level does sit within the bounds of the NavMesh.

I have the Rebuild Dynamic NavMesh during run-time enabled in my config.

The only difference is that the floor tile of the first part of the video, this floor tile was placed in editor and the floor tiles in the maze gen are inside aactor blueprints containing a static mesh (same mesh as first part) and placed during run-time.

How come it doesn’t work anymore ? Is it a Bug ? Is it Intentional ?
How come it works if you place stuff in editor but not spawned at run-time even with rebuilding the navmesh during run-time?

#Please Epic


Hey Saxon,

There have been some known issues with Nav Meshes rebuilding at runtime that have been fixed internally. I can’t say for certain that the fixes will be in 4.2, but it seems likely. Thanks for the report, and please let us know if you still have the problem after the 4.2 update.


Ben Halliday

Thank you for the help Ben!