I believe the necessity of a navmesh is a limitation to the Get Random Point’s functionality and thereby intended. The random vector is derived from the navmesh.
I think you may be seeing a discrepancy between world and local vectors. The “Add Instance” node is relative to the component and uses local space, while the get random point will return world space. Try changing the math to offset the location vector by the actor’s location. Like so:
Let me know if that fixes the random placement of meshes going off the navmesh.
I am not entirely sure what was lost in the copy and convert then, but I’m going to suggest you try right-clicking the project file and select “Switch Unreal Engine Version”. If you can set that manually to 4.8 and try running from there, we’ve seen that fix similar problems. Otherwise, I’ll see about helping you update those individual files associated with the random point generation.
Let me know if that helps!