OK. Been digging around in the Database Query Log (DBQL) and have found a that Tableau submits the following query :
FROM dbc.TablesVX t LEFT JOIN dbc.ColumnsVX c ON c.DataBaseName = t.DataBaseName AND c.TableName = t.TableName
WHERE t.DatabaseName = 'D_DWCDB'
AND t.TableKind IN ( 'E' , 'P' )
ORDER BY t.DataBaseName,
In Tableau 8.1 The metadata call was made using the TablesV so the initial call will take into account access rights. In addition to that the query is only looking for Stored Procedures and External Stored Procedures ( t.TableKind IN ( 'E' , 'P' )) which seem totally irrelevant.
I have found a work around by cancelling the metadata query but I shouldn't have to do this.