The time available for the module to generate the file for Amazon during the CRON task is not enough. You need to set as many CRON as required by your server in order to let the module generate the file in its entirety. To learn how many CRON you need to set it is enough to start a Sync Offers operation checking the “Use CRON mode” box: check how many cycles are required and how long each of them takes, then set the same number of CRONs at a temporal distance greater than the one each operation requires.