The 'thank you for entering' confirmation message was working perfectly yesterday (I know, because I tested it!), but seems to have dropped off overnight on the MA competition (although it is working on the Lindy one, bizarrely).
I have alerted our tech team who are on the case and will fix it asap. In the meantime, I've set it so that if you enter and then try entering again you'll get a message confirming you've already entered, so you won't be able to again.
And don't forget, you must be logged in for the questions to appear.