RESOLUTION
The issue is lying on Sharepoint server side.
Changing the name of a list in server side will result in failure to retrieving the metadata of the site.
For Sharepoint 2013 server, it could resolve the issue by upgrading the server with the latest patch KB3115174.
In the notes for two of the KBs, it included a “cumulative” KB, KB3115168 (for sharepoint “server”) and KB3115177 (for sharepoint “foundation”).
When you use Excel PowerQuery that uses the ListData Service to connect to a SharePoint list, you receive the following error message:
OData: The feed's metadata document appears to be invalid.
This issue occurs if the list begins with a number and contains a choice type column.
Our tests really show us that: to cause the error, a list has to:
* Have its name start with a digit, AND
* Contain a choice type field
For Sharepoint 2010, the issue still exists after applying the latest patch (KB3115245) for the server.
If using 2010 version of Sharepoint, it seems that the workaround is NOT to create the list like that.
STATUS
There is also an issue when trying to import/export into Sharepoint 2013 .
TIC-12684 has been opened for this issue and it will be fixed in the next version of Toad Data Point.