The total consumption allocated to nodes from Loadbuilder (such as with the Proportional Distribution by Area method) is less than the total flow in the flow boundary polygon, due to the service areas not extending to fill all flow boundary polygons. What Can I do?
In a case where the flow boundary polygon extends beyond the outtermost edges of the model, you can consider using the "Polygon Boundary layer" option in the Thiessen Polygon tool. This is an alternative option to the "buffering percentage", which will extend the service area polygons of each node to fill the flow boundary polygon. So, you could create a shapefile with one single polygon spanning the bounds of your "flow boundary" layer and use that to generate the Thiessen polygon.
Thiessen Polygon generated with 10% Buffer Percentage:
Thiessen Polygon generated with 70% Buffer Percentage:
Thiessen Polygon generated with Flow Boundary polygon: