title: Data binding of lightning:input and aura:attribute with type sObject(field) is not working
body: <p>There is a weird scenario I'm facing while I try to bind the markup UI tags with lighting aura:attribute as type sObject (fields).
  I'm trying to bind data to sobject's fields for different lightning:input tags,
  For one sObject attribute the binding works perfect, but in the same way for another sObject the data is not getting bound.
  For Ex:</p>
  
  <pre><code>&lt;aura:attribute name="student" type="JN_Student__c" access="global" default="{'sobjectType' : 'JN_Student__c'}" /&gt;
  &lt;lightning:input aura:id="requiredVal" name="lastName" label="Legal Last Name"value="{!v.student.JN_Last_Name__c}" maxlength="20" required="true"/&gt;
  </code></pre>
  
  <p>this works perfectly and the data persists as I show/hide this section.
  WHEREAS for,</p>
  
  <pre><code>&lt;aura:attribute name="insuranceInstance" type="JN_Insurance__c" access="global" default="{'sobjectType' : 'JN_Insurance__c'}" /&gt;
  &lt;lightning:input aura:id="requiredVal" name="lastName" label="Legal Last Name" value="{!v.insuranceInstance.Name}" maxlength="20" required="true"/&gt;
  </code></pre>
  
  <p>the 'v.insuranceInstance.Name' doesn't persists its value.</p>
  
  <p>Please reply if anyone knows/encounted the same.</p>