Im having the exact same issue with the latest build of Telerik AJAX Q2 2016. Ive attached a sample of my project I am working on.
Ive added in the designer code the DataDescriptionField and also in the AppointmentDataBound to assign the "Description" but it never populates in the page when I run it. The Description was populating fine, up until I used the AppointmentDatabound to set the resource styles.