I am on level 548 having this same issue. I need five 5 letter words and 5 six letter words and only get 10 tries to complete it. the middle two rows of the board are red tiles (word must end with that letter). If I make a five letter word with none of the blocked tiles, a lot of times they aren't counted. Or if I make a word that ends with a blocked tile sometimes it does recognize it and sometimes it doesn't. I can easily make five and six letter words but it's frustrating when the system doesn't recognize it because the first time it isn't recognized, my game is shot since I only get ten tries to make ten words.