Issue Macro Does Not Shows Service Desk's Custom Field

Steps to reproduce:

1. Install Service Desk in JIRA
2. Integrate JIRA and Confluence
3. in Confluence add Service Desk custom field like "Customer Request Type" and "Request Participant" in the Issue Macro's "Columns to display".
   

Expected Result:

The value of the Customer Request Type and Request Participants are showns. For example. Sprint field from Agile is shown correctly.

Actual Result:

No values are shown in Customer Request Type and Request Participants as shown in

Diagnosis:

In JIRA, the custom field does have value when filtered in the JQL as shown:

Environment:

Tested on Confluence 5.7.1 and Confluence 5.8.6
JIRA 6.3.12 with Service Desk 2.3.6