Describe the bug
In WPF, when creating any form, an exception is thrown in the constructor after calling the this.WhenActivated extension :
System.ArgumentException: 'Don't know how to detect when Dedoose.Views.MainView is activated/deactivated, you may need to implement IActivationForViewFetcher'
The same behavior is repeated when updating to the latest version 16.2.1
Screenshots

Environment
- ReactiveUI Version: 14.1.1