appearance menu adding new pages

appearance menu adding new pages .

When trying to add new pages on the ‘menu structure”, they do not drag anywhere, just gets sort of ‘extension’ with cells under the ‘page’ that I am trying to drag to position. It never happened before. I tried with mac, with windows, with different browsers and still is the same problem. So Basically, can’t add more pages into menu or change the position of existing ones.