Using AddServiceLayers Causes Warning and Failure to Add Layers

I'm using the function call below in an attempt to add a service layer to the map. 

 

this.app.site.essentialsMap.addServiceLayers([_esriDynamicLayer], "Operational");

 

I get a warning in the console saying "[warning]: 09:19:53.270: Cannot create highlight layer because layer with name 'defaultHighlightLayer' already exists." and the layer is not added to the map.

 

Does anyone know what's going on here? 

 

HTML5 2.5.2 viewer

 

GE 4.4