The flow direction arrow symbol from a map service does not display when added to a web map in Portal for ArcGIS

Description

Flow direction arrow symbols applied to an individual Map Service layer do not display when the layer is added to a web map in Portal for ArcGIS. Instead, thick black lines appear in the web map.

The image below displays what happens when an individual Map Service layer using flow direction arrow symbols is added to a web map. It is apparent that no symbols are rendered:

However, when the same Map Service layer is opened in ArcMap, flow direction arrow symbols display correctly as shown in the image below:

Cause

This is a known limitation. When added individually, Map Service layers containing flow direction arrow symbols are not supported and will not draw as expected when added to a web map. Web browsers do not have the ability to draw complex line symbols. If there are multiple line layers or line layers with complex symbols, the lines are downgraded to simple line symbols. For more information, refer to ArcGIS Server Web Help: Define Symbology.

Solution or Workaround

As a workaround, add the complete Map Service URL to the web map in Portal for ArcGIS instead of only adding the individual layer that contains flow direction arrow symbols. For more detailed steps, refer to Portal for ArcGIS Web Help: ArcGIS Server web service.

Note:
If flow direction arrows are not visible on the web map, zoom in to the area of interest.