The Edit operation fails when trying to add a new row to a related table in ArcGIS Pro.

Workaround

1. Add a new GUID field to the table, and set the Allow Null Values to Yes.
2. Calculate the GUID values to the new GUID field.
3. Delete the relationship class.
4. Delete the GUID field.
5. Create a new relationship class to replace the one deleted in Step 3.

Steps to Reproduce