Please try and use your native camera instead of the app camera, if this does not work then input the numerical one-time code into the app instead.
If you are continually unable to scan the QR/numerical codes displayed, please make sure that your app is up to date in the App store and also delete your cache and cookies and then try to scan again. If this still doesn’t work then please, Ask a Question and we will investigate this and advise you when this has been resolved. In the meantime we ask if you could request that your lecturers mark your attendance manually where possible.