Fix T83344: Cycles baking with progressive refine fails on GPU

intern/cycles/render/session.cpp

@@ -560,11 +560,13 @@ bool Session::acquire_tile(RenderTile &rtile, Device *tile_device, uint tile_typ
   if (read_bake_tile_cb) {
     /* This will read any passes needed as input for baking. */
     if (tile_manager.state.sample == tile_manager.range_start_sample) {
+      {
         thread_scoped_lock tile_lock(tile_mutex);
         read_bake_tile_cb(rtile);
       }
       rtile.buffers->buffer.copy_to_device();
     }
+  }
   else {
     /* This will tag tile as IN PROGRESS in blender-side render pipeline,
      * which is needed to highlight currently rendering tile before first