3819300 - Import Data Error: "Cannot expand named range" when importing a Custom Field Drop Down file

I have a Custom Field Drop Down excel file which I need to upload to a company.
Whenever I go to Import Data, add a new task and select this file, I see a red warning icon in the Status column once the file is completed. When I select the page checkbox icon to see Details, I see an Error in the log box saying

"Cannot expand named range"

When uploading a Custom Field Drop Down file, I get an error once the file is completed. Error says "Cannot expand named range". This can de bue to the file's values being under or over the data type length or the file being corrupted. , KBA , CON-CA , Cross Applications , CON-CA-CMP-IMD , Import Data , CON-CA-CMP-MCF , Manage Custom Fields , Problem