Using the Link External Data Synchronisation Tool can be problematic when importing from an excel spreadsheet data source. In particular, if the first row of data is intended to contain the names of the columns/fields, these can be misinterpreted as being the first row of the data. The fault actually appears to be a fault in the data source, rather than the data sync tool. It also seems that the data source interpretes the data as numeric rather than strings. One possible way round this is to convert the data to CSV format, and use the CSV data source instead.
