If the 'Activate Touch Interface' node is called in blueprints (set to a non-'None' interface) and the current touch interface is set to 'None', the editor crashes.
1: Open a blank project.
2: Edit->Project Settings->Input->Mobile->Default Touch Interface, click on the dropdown, type 'none' and hit enter. Close the Project Settings window.
3: Open the Level Blueprint and create the following nodes:
Event Begin Play -> Activate Touch Interface
From Activate Touch Interface, pull out the Target pin and select 'Get PlayerController'.
4: Set the 'New Touch Interface' from the 'Activate Touch Interface' node to DefaultVirtualJoysticks. You have to click the View Options at the bottom of the dropdown and select 'Show Engine Content'.
5: Compile the blueprint and Play In Editor.
Head over to the existing Questions & Answers thread and let us know what's up.