We are facing the error that files transferred from iOS app which is managed by Intune MAM to Teams is broken and cannot open it. We would like you to fix this issue smoothly.

Effected device :
　・iOS device (10.2 / 11.3 etc.)

Intune Settings :
  ･Intune MAM Without MDM management
  ･Same MAM setting are assigned to OneDrive / Outlook / Teams / Excel (File Transfer between apps settings / Copy and paste between apps settings is all “Policy Managed apps”)
Azure AD Portal (https://portal.azure.com/) > Intune > Mobile apps > App protection policies > iOS Policy > Settings
  ･All apps installed on iOS devices are latest version, and they are all managed by MAM

Activity :
As the image in the attached file shows, the error is reproduced with below steps.

1. Save Excel files which is created at iOS on OneDrive.
2. Preview those files from OneDrive. Choose “Send Copy” via Open in > Select Teams > Specify the direction and send with Excel files.
3. Open Teams on the same iOS device, and refer those Excel.
4. “Cannot open file” message is shown.

For isolation the issue, we conducted below steps :

  ･Same error is occurred even if the apps are changed from OneDrive to Outlook
  ･Same error is occurred even if the attached file is Office Word
  ･File is opened in Teams properly if the iOS device is not managed by Intune.

From above circumstances, the impact area should be all iOS devices, and we assume that how to receive files by Teams which is managed by MAM is the cause of issue.
It also seems the file is broken as of it attached on Teams.