Navigation mesh problem with a demo level


I have a problem regarding the navigation mesh. I am developing my game in a demo level, and I have an AI citizens so I need the navigation mesh. The problem is the navigation mesh is not applicable to all the landscape. There are some areas where the mesh does not work and I am not very familiar with the level design.
Thank you,

Depending on angle and height it will not generate . I’d recommend looking for the unreal twitch channel they did a live stream on the nav mesh. Also there is a short wtf is nav mesh YouTube video

The citizens are already generated but they don’t move, I have tried them in another level and it worked the problem in the demo level which I am working on.

Can you make a screenshot of your demo level (zoom out to get the most of the level/terrain and then press the key “P” to show the navmesh bounds?). The navmesh will turn green and it is normal behaviour, so don’t panic :).

Thank you all I have solved it.