When practicing with the German flashcards (Level 1 / Session 3) it generally expects 'Danke' for 'Thanks' but there are other times when it expects 'Danke schön' for 'Thanks'. The only way I can tell which phrase to use is 'Thanks = Danke' and 'Thanks. = Danke schön' The only difference is the period.
Not sure if this is a bug so I've taken two screenshots but I don't think I can upload them to a forum post.