LM5025: OUTB level shift circuit fault

Hi guys

I use the LM5025 to build a flyback converter. A level shift circuit is applied to OUTB to generate negative voltage for low side P-MOS, the circuit is shown in Figure 1. Recently, we found that if R62 in the level shift circuit became very large (can be considered as open circuit） and cause a fault. My questions are followed:

1. If R62 is open circuited, can P-MOS be turned on or off ? And how this happened?
2. Why OUT B output changed? If R62 is very large, the OUT B PWM seems shorter compared with nomal condition. Waveforms are showed in Figure 2, CH1 is normal OUT B PWM, the Ref 1 is fault OUT B PWM.
3. The change of OUT B PWM seems changed OUT A PWM too(also shorter than normal one). Why this happened?

                        Fig.1

Cheers

JIATIAN