Can you confirm if this issue is only occurring with feature services hosted in ArcGIS Server? If so, what is the version of ArcGIS Server?
Things to consider:
- Does the service have multiple layers? If so, are you adding on the layer level or service level?
- https://<arcgisserver>/arcgis/rest/services/EmergencyFacilities/MapServer versus https://<arcgisserver>/arcgis/rest/services/EmergencyFacilities/MapServer/0