Excel can't handle more than 1M rows in a single file, so given that your data is larger than that you'll need to use something else beside the Excel Add-In. If your Tableau maintenance or subscription is current then you can download and install the new Tableau Prep. (Don't be confused by the 2018.1 release number, Tableau Prep can generate .tde and .csv files for earlier versions of Tableau).
The add-in I have is Tableau7.xlam
Is there an update to this? Or is this Tableau Prep
I am running Desktop Tableau 10.5
Just to clarify I note the following:
1) In Excel my data is only say 40,000 rows.
2) In using the Tableau7.xlam the reshape tool exports as csv if (the rows generated exceeds 1,000,000 rows) but as xls if less than this.
3) When this limit is not breached the reshaping takes much longer time to form the excel file, but much shorter if it exports to csv.
4) My question was: Is there a way to force Tableau7.xlam to generate a csv in all instances as part of the reshaping process?