Mine does that when I copy and paste, it doesn't wrap properly, I haven't found a solution, except type it in manually. Are you using a browser to edit your listing, Safari? I think if you revise the listing again using the app it might stop doing that. I was able to fix some other problems that way - text colours, it was getting confused because I have the browser in night mode and there is no way to change the text colour on the description.
