Resolution appears incorrect when using Windows Mixed reality Simulator. It appears to only take up around 1/4 the available screen space.
Result: The game only renders in around 1/4 of the available screen space (see image)
Expected: The preview of the game would render so that it takes up the full screen space available
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-69536 in the post.