LTC3632 glitch when slowly increasing Vin

Hi.

Customer is using LTC3632, he made some tests.

LTC3632  powered  from LAB power supply, when increasing slowly input voltage  from 0 , converter trying to start up (oscillate) but can set adequate output voltage  and sets 0.8-1 V or Vfb below 0.8V.  After that converter don't  work  even if Vin  is 10-20 V.

When current limit increased glitch appears less frequently, maybe there is short curcuit protection glitch or internal circuits can't start properly near  border voltage;

It's not critical problem in application, but may cause failure.

I asked customer for  schematics.