TMS320F28379D: Phase-shift PWM not functioning properly

Hello,

I am running an ac-dc converter, which uses a full bridge inverter and full bridge rectifier. All these four half bridges (two inverter half bridges and two rectifier half bridges) in the converter need to be operated at 50% duty cycle, and the phase shifts between them should be modulated according to the line cycle voltage to achieve the PFC operation of the converter.  I am using ePWMs 1 - 4 for this purpose and loading the TBPHS value of these ePWMs from the lookup table, which stores phase shift values with respect to line voltage. The below figure shows the switch node voltage waveforms of all the half bridges (1 through 4), which are driven by ePWMs 1-4, respectively.

Phase shifts of these half-bridges 2 to 4 vary in the following ranges with respect to half-bridge-1:

Half-bridge 2: 80 degrees to 180 degrees

Half-bridge 3: 60 degrees to 265 degrees

Half-bridge 4: 220 degrees to 270 degrees

Half-bridges 1,2 and 4 are switching properly throughout as expected, but half-bridge 3 is switching with a duty of more than 50% in some regions over a line cycle, and sometimes phase-shift of this half-bridge is also not as expected. Every time before such weird behavior in the duty of half-bridge 3, I also observed the period of half-bridge 3 being longer than the expected value for one cycle, as shown below.

Any comments or suggestions to mitigate this issue are highly appreciated.

Thanks.