also running Zen Cart v 1.3.9
Google Merchant Center Feeder v1.14.2

admin>tools>BOX_GOOGLEFROOGLE
select products and then whether left blank or any number of numbers is put in max and start point and click 'confirm' - NOTHING happens except after a few seconds the screen refreshes with boxes blank.

No error messages, no confirmation of creation of the file and no file in catalog/feed/google

So what is missing?