LT8315 doesn't work properly

Hi there!

I am using LT8315 as a non-isolated buck converter. The input range is 200-400V, the output is 12V 100mA (max)

LTspice simulation shows ok in the input range 30V-400V with static load 120mA.

But actually it works from 30V up to 200V and the output is 10.2-11.8V depends on the input voltage and not strongly regulated. The frequency changes from 16kHz at low input voltage up to 19kHz at 200V. If the input voltage is close to 200V or higher some kind of the protection observed and the output is drop and pulses.
Above results I have got when the LT8315 only was tested and everything else was disconnected and 100R load was used in parallel with D403.
Could someone say me pls where i am wrong?
Sch attached