Noticed the same issues, beginning last summer, when entering or editing stories while using IE (Internet Explorer). Also, all previously added stories had become run-together.
Open Ancestry.com in Google Chrome instead. When you add new stories, the spacing stays put.
To revise old stories that have become a run-together mess:
1) Start a 'new' story using Google Chrome.
2) Re-copy the text from your genealogy program, paste into the story editor, save. Check to be sure it saved properly.
3) Delete the old run-together story (you'll spend way too much time adding spaces back into the content)
Note: This will NOT correct any browser difficulties being experienced at Ancestry - it is simply one way to correct your (own) personal "stories" so that they are readable again.