Unable to go fullscreen in Standalone Game

Unable to make the Standalone Game window fullscreen with a console command or with Alt+Enter.

This is a regression as this was not an issue in 4.14.2.

Setup:
Have access to templates.

Repro:

1. Open a copy of BP First Person template
2. Play it in Standalone Game
3. Enter the console command "fullscreen" or alternatively press Alt+Enter.

Expected Result: The Standalone Game window goes full screen.
Actual Result: Standalone Game window does not change.