Did you also try your shorter Project related command with the '/expfileopt:add /exptable:Forecast /exptableopt:overwrite' included?
As I understand it doing so should not be necessary but Access can be funny sometimes it seems.
Are the Project Export parameters the same as the ones set for the batch command? Is there any possibility that for some reason in the automatic process the database you are exporting already thinks it has that table and it is protected?
Just thinking aloud.