Hello,
Teacher area.
Teacher Menu have Items:

• Quizzes/Final Exams
• Media

Each page of this Menu Items have a button "New" with dropdown sub-menu items.
If I push on "New" button but don't choose any sub-menu item and again push on "New " button (or other area of this Page), a button is disappears.
This can happen if the user changes his mind or doubts.
:-(
I reproduce this on your demo site in front end Teacher area.
Best Regards,
Lazer

the same you have on New Quiz Creation Page Tab "Question" with New Question dropdown button.