In Portal for ArcGIS 10.9.1, the web maps with an ArcGIS Online hosted layer with related tables fail to save in Map Viewer.

Workaround

Save the web map in Map Viewer Classic and open the web map in Map Viewer.

In Map Viewer:

1. Click the Add button (not the layers button, but the circle with a plus sign).
2. Click Web Service > paste the URL or REST service URL of the ArcGIS Online Feature Layer.
3. Save the map.

From the Content page:

1. Go to My Content > Click Add item > From a URL.
2. Click ArcGIS Server web service and finish the steps > click Add.
3. Create a new web map or open an existing web map in Map Viewer on Portal for ArcGIS 10.9.1.
4. Add layers and browse from My Content. Add the newly added item to the web map.
5. Save the map.

Add the services per sublayer separately via the REST service URL:

1. Create a new web map or open an existing web map in Map Viewer on Portal forArcGIS 10.9.1.
2. Add layers and browse from ArcGIS Online, and instead of using this URL, https://services.arcgis.com/nSZVuSZjHpEZZbRo/arcgis/rest/services/Energielabels/FeatureServer, opt for the separate URL of the sublayers,

• https://services.arcgis.com/nSZVuSZjHpEZZbRo/ArcGIS/rest/services/Energielabels/FeatureServer/0
• https://services.arcgis.com/nSZVuSZjHpEZZbRo/ArcGIS/rest/services/Energielabels/FeatureServer/1

Steps to Reproduce