Sometimes web browsers will glitch out with complex pages. If you're finding that you can't progress in your course because you can't click anything then this will be a browser caching issue.
All you need to do is;
Clear your browsers cache
Grab a ☕
Restart your browser
And you'll be good to go again 👍
If you are still suffering?
You could try another browser, we haven't had this issue reported with Microsoft Edge or Mozilla.