Ensure all inner compartments are properly in place and that the silicone lid insert is securely clipped under the side grooves, with nothing protruding above the edges of the box.
Sometimes a small piece of food or misaligned tray can prevent the lid from closing properly. Press down gently and evenly on the lid to secure it.
For easy cleaning and long-lasting use, always check that the bento is clean and dry before closing.