For this one, it seems that you simply haven’t populated the mobile off canvas area with any elements. It should be a simple “fix” by going to the Customiser -> Header -> Mobile view and dragging elements inside the builder — https://ibb.co/kVTMhgJ
You could also check out this comprehensive guide — https://creativethemes.com/blocksy/video-tutorials/customization/understanding-the-mobile-header/ — on how to work with the mobile header. 🙂
Hope this helps!