When I create my own lesson using an apostrophe character, and then launch it, the apostrophe is not recognized. The character works perfectly during the configuration of the lesson, there are no errors, but as soon as the lesson is triggered that key will not work and only the mistake highlight pops up, and will not let me continue. This is happening on both versions, online and the downloadable app. If you want I can share some snapshots or video capture for further details.
Thanks.

Thank you for your message. We tested your "I'm" lesson with exactly the same configuration like yours: OS X, Chrome and an US Qwerty keyboard. It works.
Also when we choose the screen keyboard under OS X it also works.

It seems like your keyboard is writing a different character than "'", for example "`" or "´"?

It would be nice if you could help us solving the problem. Can you please try as a first step a different browser?

All the best from Berlin,
Your Tipp10 Team