Symptoms
When a workflow that can be started when a button is pressed inside a form. Information can such as properties can be missing from events such as email events, even though the SmartObject properties have been assigned in the correct fields.
Diagnoses
This issue can be because the start rule for the workflow was specified on a button click and that there was no list reference set within the workflow. This can be the reason as to why properties are not being passed in the a field within an activity.
Resolution
To resolve this issue we created the reference ID for the workflow as a data field and specified that within the Get item reference (the method that was used in this particular instance) the data was then retrieved successfully. Ensure that the workflows reference ID matches with the form.