WebCamTexture not working on Windows Phone 8.1

I've been trying to get WebCamTexture to work on Windows Phone 8.1 but have been getting the following error:

 Error: Operation has failed with error 0x80028019: Old format or invalid type library.
     
  (C:/buildslave/unity/build/PlatformDependent/MetroPlayer/VideoTexture.cpp:WebcamTexture::Play at 410)

This is on a new project with just a RawImage on the scene and the following script attached to it:

 WebCamTexture webcamTexture = new WebCamTexture();
 RawImage rawImage = GetComponent<RawImage>();
 rawImage.material.mainTexture = webcamTexture;
 webcamTexture.Play();

The phone is a HTC 8X running WP 8.10.14203.306. WebCam capability in publishing settings is checked. Build SDK is Windows Phone 8.1.

Does anyone know why is this happening?