Looking at those traces there's nothing obviously wrong with the input to the driver, so the issue would seem to be with the driver, yet you say it works ok with a pulse generator?

Are the motors clamped down to the bench? I know my bench testing was noisy when the motor was just lying there.

Do you have PIC ground and motor supply ground tied together or separate?

What do you have on input & output of 7805 regulator?