Why is the message “Some functions of this app may not be supported in DeX” displayed?

This message appears when an app does not support the Multi-Window feature. It informs the user in advance that the app may function unexpectedly. If the app developer introduces support for multi window display, it will function properly in Samsung DeX.

We are communicating internally with app developers to ensure that more apps can be optimised for Samsung DeX and thus function adequately. 

NOTE: Multi-Window: This feature is supported to display more than two apps simultaneously on a device running Android 7.0 Nougat or later version. By activating this feature on an app, the user can resize the app freely.