Hi @HaiHoangSoftware
This will happen only first time because it is necessary to copy the firmware to passive partition. The device works as usual after reset, just HSE_STATUS_INIT_OK is set later after about 1s, so you can't trigger HSE services until the HSE_STATUS_INIT_OK is set.
In earlier versions of firmware, the firmware was copied to passive partition after each AB swap (even if the firmware was not updated). If you have firmware 0.2.50.0 for S32K396, this was changed to reduce this delay - copied from release notes:
"In ABSwap reduced HSE init time after Partition swap and reset by skipping firmware backup if HSE FW is the same"
So, you will see 1s delay only if the firmware is being updated.
Regards,
Lukas