[SUPPORT] Advanced Turn Based Tile Toolkit

Ah, I see. From your example it might simply be that the collision of your mesh is not tall enough to block the trace (provided the mesh has a properly set up collision volume). Traces happen at VisibilityTraceHeight, defined in BP_GridManager. For debugging you might want to go to the CheckIfTileIsVisibleFromOtherTile function and enable DrawDebugLine in the LineTraceByChannel function call therein.