I am trying to use a spline to modify the navmesh. I came across the SplineNavModifier component and added it to a new actor in a brand new project. It seems the actual resulting modifier area (blue lines) is offset from the spline itself based on the containing actors world location. It also appears if I bring the actor too far from the world origin it no longer works at all. Is this component bugged or is there something I may be doing wrong?
This is a bug in the engine. Planned to be fixed in 5.8
In case you have a source build of the engine, then check line 105 of SplineNavModifierComponent.cpp
Currently the AreaNavModifier is assembled there using the spline component’s transform - which in the end leads to transforms being applied twice. Instead just pass `FTransform::Identity` into there and the offset is gone 
FAreaNavModifier NavModifier(Tube, ENavigationCoordSystem::Type::Unreal, FTransform::Identity, AreaClass);