This one got me again. The hint for 'ojqu' comes up with an empty word bubble. Don't remember seeing it in the list of known issues, so I'll try and put an entry in when I get a chance. I'm on the mobile version(android).
Known issue number 2 at https://forum.duolingo.com/comment/26778885 : "words that begin with an apostrophe, such as 'IH (beautiful), 'ej (and), or 'oH (it) do not display hints."