Android devices do not show up class materials folder. Urgent Problem!

We are a school with 800 students using Teams since yesterday. The class materials folder does not show up on Android devices. Students cannot see exercices teachers provided for them. iOS and PCs work fine though. It is the folder Teams creates automatically (read only rights for students). Manually created folders show up. I even contacted customer support but the (nice) man could not help me because it is a problem with the app and not with the Windows OS. I hope anybody can solve that problem.