Hello again @Katarina_Koren!
Thanks to you we've now managed to find and patch this problem!
The fix has been included in the latest version of the iPad app which will be available on the AppStore soon. As soon as it becomes available I will update you here so you and your students can update to the latest iPad version of EF Class and stop experiencing this issue.
Thank you very much for your extremely valuable feedback!
The EF Class Team