Index: lams_tool_preview/src/java/org/lamsfoundation/lams/tool/peerreview/web/controller/MonitoringController.java
===================================================================
diff -u -rca958ecbc65696caf0f399cec0a8eace5a84da98 -r7d4a3f612eb7ea53f43052f9990aadc818243ca9
--- lams_tool_preview/src/java/org/lamsfoundation/lams/tool/peerreview/web/controller/MonitoringController.java	(.../MonitoringController.java)	(revision ca958ecbc65696caf0f399cec0a8eace5a84da98)
+++ lams_tool_preview/src/java/org/lamsfoundation/lams/tool/peerreview/web/controller/MonitoringController.java	(.../MonitoringController.java)	(revision 7d4a3f612eb7ea53f43052f9990aadc818243ca9)
@@ -26,6 +26,7 @@
 import java.io.IOException;
 import java.text.DateFormat;
 import java.text.SimpleDateFormat;
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Comparator;
 import java.util.Date;
@@ -121,15 +122,16 @@
 	sessionMap.put(PeerreviewConstants.ATTR_IS_GROUPED_ACTIVITY, service.isGroupedActivity(contentId));
 
 	List<RatingCriteria> criterias = service.getRatingCriterias(contentId);
-	PeerreviewServiceImpl.removeGroupedCriteria(criterias);
+	List<RatingCriteria> flattenedCriterias = new ArrayList<>(criterias);
+	PeerreviewServiceImpl.removeGroupedCriteria(flattenedCriterias);
 
-	if (criterias.size() == 1 && criterias.get(0).isRubricsStyleRating()) {
+	if (flattenedCriterias.size() == 1 && flattenedCriterias.get(0).isRubricsStyleRating()) {
 	    Map<Long, Map<PeerreviewUser, StyledCriteriaRatingDTO>> rubricsData = getRubricsData(sessionMap,
-		    criterias.get(0), criterias);
+		    flattenedCriterias.get(0), criterias);
 	    request.setAttribute("rubricsData", rubricsData);
 	}
 
-	request.setAttribute(PeerreviewConstants.ATTR_CRITERIAS, criterias);
+	request.setAttribute(PeerreviewConstants.ATTR_CRITERIAS, flattenedCriterias);
 	return MONITORING_PATH;
     }