Questions Hanged in Practice
In learning German for English speakers questions in practice get hanged and do not move forward. The button "Continue" becomes dim. The only way to solve the problem is to refresh the page after which I have to start again from the beginning i.e. a new session starts. It happens frequently. Refreshing again is not a great deal for me but I feel I should let it know.
I have faced this issue a few times. It could be a slow internet connection issue at your end or server capacity issue at Duolingo end.
Also, Duolingo seems to work better on Chrome browser. You can try this.
I use Chrome browser and the best internet connection available in Bangladesh. I have never had any problem related to speed. I used Zendesk with this connection. It could be the server capacity issue of Duolingo due to huge number of users. Thank you for sharing your experience.