MCU Firmware Missing

Hi,
Sometimes Mcu Firmware Missing suddendly .

Device Details:
Device: WP7608
Firmware Version: SWI9X07Y_02.16.02.00 000000 jenkins 2018/04/19
19:59:02
Bootloader Version: SWI9X07Y_02.16.02.00 000000 jenkins 2018/04/19
19:59:02
MCU Version: 002.009
Legato Version: 18.06.3_69d8a71199a354ce67a45989abdf0967_modified

Observation:
-Application didn’t crash its working normally
-Manually poweroff and turn on the device MCU firmware is missing
-It will recover once it hard restart the device.

Kindly let me know the reason ASAP
Thanks in advance

how about using latest FW R13.x?