MySQL for Excel 1.3.8 Connections Missing from Dialogue Window
Simply start up Excel, click on File at the top left, click on Options at the bottom left, select General in the Excel Options dialog and under User Interface Options select Optimize for Compatibility, click OK and restart Excel.

optimistic updates combined with collation-server may lead to erroneous updates

You can workaround the above type of MySQL Errors if you either disable the optimistic update setting, or by removing the collation-server setting, if possible.