diff --git a/applets/taskmanager/package/contents/ui/GroupDialog.qml b/applets/taskmanager/package/contents/ui/GroupDialog.qml
--- a/applets/taskmanager/package/contents/ui/GroupDialog.qml
+++ b/applets/taskmanager/package/contents/ui/GroupDialog.qml
@@ -262,7 +262,7 @@
         // Setting VisualDataModel.rootIndex drops groupRepeater.count to 0
         // before the actual row count. updateSize is therefore invoked twice;
         // only update size once the repeater count matches the model role.
-        } else if (!groupRepeater.aboutToPopulate && visualParent.childCount == groupRepeater.count) {
+        } else if (!groupRepeater.aboutToPopulate || visualParent.childCount == groupRepeater.count) {
             var task;
             var maxWidth = 0;
             var maxHeight = 0;