I have similar issue. I’m using 1 level(Map) in 5.3 and World Partitioning. When I start at initial point and first world cell, the nav mesh is good. But when I move to the next cell, it’s not loading(all actors are being loaded but NavMesh).
I also went through tutorial. After build of Nav Mesh(step number 4), it stopped loading at all(even at initial point in Partitioned Map).
I don’t think setting generation level to Dynamic from Static is really good fix. It will affect performance and quality of nav meshes at some cases. There should be something with Static mode too.
This post has helped Nav Mesh and Streaming Levels - #2 by Swe08