JIRA Portlet Macro not displaying when authenticating using the trusted application between JIRA and Confluence

We're having issues using the JIRA portlet macro (jiraportlet) on pages inside Confluence.

Whenever we try to use this macro using the trust between JIRA and Confluence for authentication, the macro does not display on the page. There aren't any errors, it just doesn't appear.

{jiraportlet:url=http://localhost:8081/secure/RunPortlet.jspa?portletKey=com.atlassian.jira.plugin.system.portlets:mywatches&numofentries=10&showTotals=false&}

However, if I specify a valid JIRA username and password by adding the os_username and os_password parameters to the URL, the macro displays properly.

{jiraportlet:url=http://localhost:8081/secure/RunPortlet.jspa?portletKey=com.atlassian.jira.plugin.system.portlets:mywatches&numofentries=10&showTotals=false&os_username=user&os_password=pass}

I believe the trust is working, as I can pull in issues properly using the JIRA Issues macro. (Our JIRA installation doesn't allow anonymous access, so all requests need to be authenticated)

Authentication for both applications is configured to use Crowd with external user and group management. Both applications share the same underlying group and user store (Active Directory).

We're running the following versions:

• Confluence 2.7
• JIRA 3.12.1