diff --git a/packages/editor/src/components/tools/item/use-placement-coordinator.tsx b/packages/editor/src/components/tools/item/use-placement-coordinator.tsx
index 8edc1207d..192425502 100644
--- a/packages/editor/src/components/tools/item/use-placement-coordinator.tsx
+++ b/packages/editor/src/components/tools/item/use-placement-coordinator.tsx
@@ -1252,6 +1252,13 @@ export function usePlacementCoordinator(config: PlacementCoordinatorConfig): Rea
 
     const onShelfMove = (event: ShelfEvent) => {
       has3DPointerDrivenMoveRef.current = true
+      // Guard against null ref. The mitt event listener can fire after the
+      // component unmounts (or before the <group ref> attaches), and the
+      // unguarded `cursorGroupRef.current.rotation.y = ...` write below was
+      // the source of EDITOR-BC (`Cannot read properties of null (reading
+      // 'rotation')`) — 53k+ events. Every other surface-move handler in
+      // this file already has this guard; onShelfMove was missed in #323.
+      if (!cursorGroupRef.current) return
       const ctx = getContext()
       if (ctx.state.surface !== 'shelf-surface') {
         // Cursor entered via a move event without an enter — try