MIT App Inventor wont let 2 of my students access their code

I have a class of 18 students who are working in App Inventor. 2 students(who are the best coders) can not access their work or transfer it to a tablet. They get the message - ooops we have stepped on a bug.

We have restarted their computers, and made sure it was up to date on all software updates and it still will not work.

We were planning on presenting the apps tomorrow.

If you send me a private message with some of the account names we should be able to take a look and see what's going on.