LTC3882-1 issue


I ran into an issue using LTC3882-1 in our custom design. We are using LTC3882-1 together with UCD7242 to generate 1.0V core Vdd for LS1046A processor. Only channel 0 of LTC3882-1 is used, channel 1 was set to be off. I am trying to figure out the source of a power glitch, where pin 7 (PWM0) was interrupted for ~140ms before recovered itself. See the below scope capture for reference. Signal 1 is pin 7 (PWM0) of LTC3882, signal 3 is 1.0V rail. 

When I read the status via I2C, channel 0 reads 0x0000 at 0x79, and channel 1 reads 0x0840 at 0x79. Also the fault log is empty at 0xEE. So the chip LTC3882 does not flag any error. All the signals around the chip are also verified to be OK. Can you please recommend where I can look at? This issue happens when our custom board draws ~2.2A on 3.3V power supply.