When publishing from ArcMap to ArcGIS Online, data represented by null values are not symbolized on the map. To ensure the data are displayed, null values are symbolized differently on the map.
The attribute table in the image below shows the null values in the PICKPOCKET column before publishing to ArcGIS Online.
The image below is the published map showing the distribution of pickpocket incidents in Florida. Features with null values are not displayed on the map.
The problem occurs due to the null values in the dataset. Null values represent no data or no value, and are therefore not symbolized on the map.
Choose one of the following methods to symbolize null values in a hosted feature layer in ArcGIS Online:
Configure from ArcGIS Online
The image below shows the newly populated data. Null values are represented by the gray area, while coded values are represented by the chosen symbology.
Configure through ArcMap
Note: If there are zero values in the dataset, the other option is to represent null values with numbers out of the data range, such as -99 or -999. Refer to FAQ: How do you represent NULL values when converting from a geodatabase, or shapefile, to a coverage?
The image below shows the newly populated data on the map. Null values are now represented by the value zero.
Note: In cases where the attribute table cannot be edited because the service is overwritten with null values, follow the steps below to update the attributes: 1. Navigate to the Settings tab of the items detail page. 2. In the Feature Layer (hosted) section, check the Enable Editing check box. 3. Scroll to the What kind of editing is allowed? field, and select the Update attributes only option. 4. Click Save. Choosing this option may require future Settings changes to enable other forms of editing the hosted feature layer.