This is no longer reproducible after the April 2018 update of ArcGIS Online.
解决办法
In the Organization tab, click EDIT SETTINGS > Utility Services. Keep the position of the Esri World Geocoder at the top most position, and click Save.By keeping the ESRI World Geocoder at the top most position, it would by default be required to click the desired users locator when adding the CSV to Map Viewer in the 'Add CSV Layer' window, and the location fields are correctly populated in the drop-down as per the users locator.