PROBLEM
When using the Edit button in ArcGIS Online Map Viewer, or using the Edit or Smart Editor widgets in Web AppBuilder for ArcGIS, multipoint features are not added to a feature service.
This is a known limitation. Adding multipoint features in the ArcGIS Online application is not supported. For more information, refer to BUG-000104054.
To resolve this issue, convert the multipoint feature class to a single-point feature class.
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