This defect is logged against a version of the software that is now deprecated. The issue is not reproducible in newer versions of ArcGIS Enterprise Map Viewer. If experiencing this behavior, reach out to Esri Support Services as a new reproduction case is needed to continue investigation.
解决办法
Option 1:
Open the problematic hosted feature layer in Map Viewer.
Select Edit.
Change the properties manually for each symbol and its fields as desired.
Option 2:
Copy a feature class data to a file geodatabase.
Add the feature class to ArcGIS Pro from the file geodatabase.
Edit the symbology: Unique Values - two fields (one of which is a subtype).
Publish the web layer to Portal for ArcGIS as a hosted feature layer.
Enable editing for the hosted feature layer on the item detail page in the Portal for ArcGIS Content page.
Open the hosted feature layer in Map Viewer.
Select Edit. The edit template assigns the symbology appropriately (same as the layer legend in the Contents pane).