self test of adxl354

We use st1 and st2 to test adxl354 during our process. We pull Standby and ST1 high during the test time, because we have other test circuit also. Test time is very high, hours. We found the sensor stop output when we toggle ST2. During the test time, we vibrate the sensor and its output won't change either. That means it still in test mode.
We change our test logic, only pull ST1 high before test the sensor, then toggle ST2 for 100mS. after that exit the self test mode. It looks good with new logic.
I searched the datasheet and didn't find relative to that logic. Is there any tricky not in the datasheet?