Polygons styled with any sort of fill complexity render as solid colours in ArcGIS Online.
Connecting ArcGIS Online to services published from slip.wa.gov.au.
This is a bug in ArcGIS Online. It only supports basic symbology for feature layers, doesn’t bring through the styling as specified in the service as published.
There are two options to work around this issue.
Option #1 - Add as a service, remove unneeded layers
You need to add the whole boundaries service https://services.slip.wa.gov.au/public/rest/services/SLIP_Public_Services/Boundaries/ and then delete the layers you don’t want.
Option #2 - Add as a feature layer, re-style it
Re-style the feature layer using the change style option in AGOL mapviewer and then add labels.