Use the green download button. The master branch may have some bugs left in it, but at the moment it has many fixes to bugs from the last release. A new release will be available soon. I’m currently using the master branch with my classes–they are the first test subjects.
Biggest thing in the new update is speed–various caching strategies have been employed to reduce the server load.
Also, try saving the item again and see if that fixes it. There was an error in the save code. The quiz is acting like there is a second invisible question with a wrong answer. Hopefully resaving the quest will fix the issue. Also make sure there isn’t an empty second question on the back end. It shouldn’t let you save an empty question, but it’s worth checking.