I have been trying with an application to provide an analog output using the Portenta but have failed to get anything other than zero output (see DAC from Portenta H7 - Portenta H7 - Arduino Forum).
Having read this post, I have just tried to make an analogRead using the Portenta H7 using the code from the analogRead reference page.
I can't get anything other than zero input, so I'm observing the same problem that was reported here. I wonder if the ADC and DAC problems are related...