PublicClientApplication cctor doesn't work on windows phone 8.1 (System.NullReferenceException)

Question

I am trying to add a simple way to connect to a microsoft account in my app using Microsoft Graph (in a c# project).

I followed the sample for UWP (https://developer.microsoft.com/en-us/graph/quick-start) and everything works fine on UWP and Windows 8.1, however I am stuck on Windows Phone 8.1 at initializing a PublicClientApplication.

private static PublicClientApplication m_identityClientApp = new PublicClientApplication("clientId", /*-optional-"authorityLink"*/);

The PublicClientApplication constructor doesn't seem to work regardless if a put as arguments one/two random strings, a valid app/client id, with or without an authority string. I have Microsoft.Identity.Client as reference in my project and have

using Microsoft.Identity.Client;

added in my .cs file. I also tried using the latest (1.1.4) or an older (1.1.0) Microsoft.Identity.Client package, nothing changed.

m_identityClientApp remains null and so my app crashes with a System.NullReferenceException exception.

I am out of ideas... :(