I am trying to get information from the designers to detail any known differences in PWM from 7026 to 7126. This will probably take another week.
In the meantime can you please clarify a point: In your scope display 3/4 along the blue trace disappears at the top because the duty cycle there goes down to zero. At about 1/4 along the blue trace partly disappears at the bottom. Is that real? I would not expect it since it looks like your duty cycle seems to be always less than about 25% based on the fact that your sine wave amplitude is about 1/4 of the digital amplitude. Can you confirm this?