Unfortunately the Houston Chronicle crossword distributor, CrosSynergy Syndicate, has requested that we no longer automatically download them in the app, but they are still available daily at http://www.chron.com/apps/games/xword/puzzles/ and can be imported via the Puzzle Calendar (the + button on Puzzle List screen) > Other.
If you're looking for a daily puzzle to replace the Houston Chronicle, we suggest either the Newsday puzzle or the Tulsa World. Our apologies for the inconvenience!