This has happened to me a couple times now... If you create a new solution, put text into both parts of the solution, and then click "Update solution," if there happens to be a formatting error (usually happens with me if I have three carriage returns in a row, or forget to close a math expression), all of the text that had been inputted is lost.
If the solution had already been successfully saved once, and then a formatting error is encountered, I can click "back" and it (either Chrome, or Quadbase, I don't know which) will remember everything I had typed. But that's not the case if it was brand new.