LTC3336

Hello,
I am using two LTC3336 power supplies for 2.8V and 3V generation. I tested my system power consumption and observed bizarre behaviour.
When the input voltage increases from 10.7V, the input current rapidly rises. What is even stranger is that if I stay close to 10.7V, for example, if the input voltage is 10.8 V, the extra power consumption will decay, and after 20 minutes, it will be close to the expected power consumption.
Please see the attached images.

Any comment?

The LTC3336 was supposed to work up to 15V. I did kill numerous LTC3336 chips much below the 15V, for which I do not have any explanation. The LTC3336 always failed by shorting its inputs and not destroying my digital circuits.

Best Regards,
Antal