I have been using the procedural mesh component and have noticed that it reacts different in the editor/standalone vs a packaged build with Nativize turned ON. If I turn OFF nativize the problem does not exist in the packaged build.
Here are some screenshots of the mesh:
This first image shows the base mesh without any editing of the vertices/normals etc.
The second image is from the New Editor Window. It shows the mesh pushed down and the normals look correct.
Here is a similar push down of the vertices/normals from the editor window showing the normals drawn on the surface.
Finally, this image shows the packaged build (development) version with the normals incorrectly calculated.
The blueprint is exactly the same in the editor and in the packaged build but this errors only shows up in the build 
I am using the standard Create Mesh Section to create the mesh then using the Calculate Normals and Tangents from Mesh then applying the normals and tangents back to the mesh with the Update Mesh Section node.
Any suggestions why this may be happening would be appreciated.
Thanks.