BQ40Z50-R1: AUTO_SHIP function

There is application for BQ40Z50-R1, the pack is in seal mode and enabled both AUTO_SHIP and IN-System_Sleep, the pack pin from BQ40Z50-R1 is always high connected to a external charger. Leave I2C bus free(no any communication but high level) , wait a longer time than auto_ship_time,  then read BQ40Z50-R1, found the SDM bit sets and CHG/DSG are “0". Check the SDM in SLUUA43, iSDM indicates shutdown triggered via command, why SDM sets during the test which has no any command send to BQ? Or Is that means when BQ40Z50-R1 decide to enter ship mode by AUTO_SHIP feather, will send shutdown command twice itself?    it's appreciated that get an answer from here.