You're trying to upload a CSV file into an Extension Field List Type, however you can't find the option in Silverlight.
The option is not available in the Silverlight version of the SAP Hybris Cloud for Customer.
For this feature you should use the HTML5 version following the steps below as example:
- Select Customers Work Center.
- Open Accounts view.
- Open Account ABC (ABC refers to the Account ID).
- Go to the Adaption Mode.
- Select Edit Master Layout.
- Hover the mouse pointer above any Extension Field.
- Select the Change Properties button (Wrench icon).
- On the sub-menu select Field Definition and on the Edit Field screen click on Edit button to enable editing.
- Click on the option Upload and browse a CSV file that is properly formatted.
- Click on the button Apply.
- Click on the button Save.
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