The missing facets result from it being a very small object.
SketchUp’s built-in tolerance is 1/1000", any points closer that that are assumed to be coincident.
So in operations like FollowMe or similar extensions like Fredo’s RoundCorner tiny geometry can result in SketchUp not creating a tiny edge, and any face associated with the unmade edge is also not created.
There is a simple workaround for this.
For a full tutorial please see Box’s thread: The Dave Method