When using a managed application and selecting the option to “Open in”, the user is unable to open the desired file into other managed destinations.
This behavior is only observed if the restriction to "Allow documents from unmanaged sources to managed destinations" is disabled as shown below, and is also only seen on devices running iOS 11.
To resolve this issue, admins must ensure that the checkbox shown below is checked on any iOS profiles applied to devices.
We have informed Apple of the issue and this article will be updated once we confirm a resolution in iOS. If you have Apple Care Support you may wish to reach out directly to Apple to learn more details around the status of this issue.