I had a problem exporting the recast mesh as an .obj
When I imported it into 3ds max, the mesh looks incorrect. It seems the vertices are transformed incorrectly and maybe the indexation is broken as well.
However, when importing into unity as an ordinary asset, it worked - well, the normals were flipped and facing down, but it works correctly.
Here is how I’ve solved it, - on 3ds max obj importer, tick “import as a single mesh” (top left corner). Additionally, ticking Reset scene might also help
Here are the images: