The ucp_pm_viewmessage.html template has an if statement to add a reported class to unapproved or reported posts.

The if statement doesn't work as it's not for PM's and was probably put there by mistake.

Line 25:

<div id="post-{MESSAGE_ID}" class="post pm has-profile<!-- IF S_POST_UNAPPROVED or S_POST_REPORTED --> reported<!-- ENDIF --><!-- IF S_ONLINE --> online<!-- ENDIF -->"> 

The if statement:

<!-- IF S_POST_UNAPPROVED or S_POST_REPORTED --> reported<!-- ENDIF --> 

I have changed S_POST_REPORTED to S_PM_REPORTED just to see if it was something simple but it doesn't work.