In testing whether a form was properly capturing UTM parameters using hidden fields on the form, I created a mock campaign URL wherein:
Original URL: http://URL.com/marketo-form-test/?aliId=5940711
utm_source = Twitter
utm_medium = Social
utm_term = GTS-2016
utm_content = Visit
utm_campaign = Organic
The form is able to successfully capture utm_source (Referrer in Marketo) and utm_medium (Medium) but for some reason utm_campaign (Source) is not being captured. I'm not quite sure why that is. It's just a blank field in the report.
Also, are there fields in Marketo that can be added to the form (hidden, too) that align to the other utm parameters?