FG60D lost config after shutdown

Unit info: FG60D, firmware 6.0.9, build0335,200121 (GA)

Problem: Unit after shutdown and power off revert it's configuration to some simple, based one.

What I've done so far:

1. I have diagnose memory - every test was PASSED

2. I have remove all old saved config revisions, just to make sure that only the most recent is present on the device.

3. I can restore the saved configuration after shutdown of the unit, then restart unit (without the power off) and everything is ok. But if I shutdown the unit, disconnect from power, plug back in, the unit revert its config to based one.

4. The option set cfg-save auto is present in the configuration.

5. All interfaces are working without problems.

Any tips what I can do is much appreciated.