The text to speech gets stuck few times every day. In this state text to speech doesn’t play any of the words that are pressed directly or via the button. Occasionally it will stay stuck indefinitely, sometimes after few minutes it will then play those words that were pressed while it was stuck. Sometimes only restarting the browser will help, but that’s kind of a drag.
This happens when changing tabs or continuing to the next lesson while audio was still playing. The solution is to play audio on the current lesson and pause the audio again. This will make the Text to speech work again.