Fix regression issue. Turns out LabelUtil.itemToLabel has side effects and text was not updated on control unless called
diff --git a/frameworks/projects/spark/src/spark/components/DropDownList.as b/frameworks/projects/spark/src/spark/components/DropDownList.as
index e4dbd96..b6dfa01 100644
--- a/frameworks/projects/spark/src/spark/components/DropDownList.as
+++ b/frameworks/projects/spark/src/spark/components/DropDownList.as
@@ -367,11 +367,13 @@
     {
         if (labelDisplay)
         {
-            if (displayItem == undefined)
-                displayItem = selectedItem;
-            else
-                labelDisplay.text = displayItem != null ? LabelUtil.itemToLabel(displayItem, labelField, labelFunction) : prompt;
-        }
+              if (displayItem == undefined)
+                  displayItem = selectedItem;
+              if (displayItem != null && displayItem != undefined)
+                  labelDisplay.text = LabelUtil.itemToLabel(displayItem, labelField, labelFunction);
+              else
+                  labelDisplay.text = prompt;
+		}
     }
 }
 }
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