There is nothing wrong with your session class. However, it is marked as
[System.Xml.Serialization.XmlTypeAttribute(AnonymousType=true, Namespace="http://www.xmlns.cfins.com/cfins/services/publishPolicyData/1.0")]
which pretty much means that xml deserializer will only consider sub-elements of your session
that are in the same xml namespace.
In short, adding ugly namespace definitions to your xml file like so:
<properties xmlns="http://www.xmlns.cfins.com/cfins/services/publishPolicyData/1.0" ...
will do the trick: you'll get all your sessionProperties and sessionData where needed.