[SS4] .NET exception at rdLink_SetFirstCorridorCrossSectionView

I have very little geometry in the file I'm working with at the moment. Just corridors, and not very refined. I think all I have in these corridors are template drops and parametric constraints. I'd been looking at plenty of cross sections. I applied a couple new parametric constraints. When on the dynamic cross section view, I skipped back to the beginning of the alignment, I got this error stack:

System.Exception: Base geometry is null.
   at Bentley.Civil.Geometry.Model.LinearEntity2d.EvaluateGeometry()
   at Bentley.Civil.Geometry.Model.LinearEntity2d.get_Geometry()
   at Bentley.Civil.Geometry.Model.Accessor.PlanLinearEntity.get_GeometryExt()
   at uGeometricEntity._GetGeometryExt(uGeometricEntity* , RefCountedPtr<IBcLinearEl>* )
   at rdLink_SetFirstCorridorCrossSectionView(Int32 , Double* )
   at Bentley.Civil.RoadwayDesigner.RoadwayDesignerPlugin.DisplayCrossectioninView(CrossSectionDisplay crossSectionDisplay, Int32 viewIndex)
   at Bentley.Civil.RoadwayDesigner.RDManager.DisplayCrossectioninView(CrossSectionDisplay crossSectionDisplay, Int32 viewIndex)
   at Bentley.Civil.CadSystem.Microstation.MstnViewManager.FirstStation(String unparsed)
   at Bentley.Internal.MicroStation.CoreHook.DispatchNoHandler(UInt32* argStack, UInt32 mysp, IntPtr pFunc)
   at Bentley.Internal.MicroStation.CoreHook.Dispatch(UInt32* argStack, UInt32 mysp, IntPtr pFunc)

Using Geopak SS4 .878.