Registered data published before an upgrade does not work with the mapping item parameter when using the Clone Item script to clone a web map if the feature service was added to the ArcGIS Enterprise portal or the web map through the 'add Item from URL' option.
This issue is not reproducible in-house and will not be addressed at this time. If the issue persists, contact Esri Support Services.
解决办法
If published to a federated server, add the feature layer to the web map that was added to the ArcGIS Enterprise portal when the registered data was published instead of adding the service to the portal through the ArcGIS REST APIs URL.
Replace the registered data published to 10.7.1 with the republished registered data from 10.8.1 in web maps to be cloned with the mapping item parameter.