Lightning:recordForm onSuccess event not returning response

Question

I'm trying to get the response in the onSuccess callback for a lightning:recordForm save event, but it's coming up as undefined. The callback is being called, I can log to the console, but both of the following lines return undefined:

let payload = event.getParam('response');

and

let payload = event.getParams().response;

console.log(payload);

undefined

Has something been updated in Spring 2019? Is there a difference between the EditRecordForm and the edit for the RecordForm?

Component code:

<aura:if isTrue="{! v.showForm}">
        <lightning:recordForm onsuccess="{! c.updateInfo }" objectApiName='Contact' fields='{! v.fieldList }' recordId="{! v.recordId }" mode="view"/>
    </aura:if>

Controller:

    updateInfo: function(component, event, helper){
    console.log('in update info, the event: ', event, ' the helper: ', helper);
    let payload = event.getParam('response');

    console.log('the payload: ', payload, 'the payload fields: ');
    helper.setClinicianInfo(component, helper);
}