Just for the heck of it, I tried compiling an ArcGIS Runtime for Windows Store app using .NET Native in the VS2015 Preview. Didn't work for me, unfortunately . Here's compile error I got:
Unexpected: could not find an unspecialized version of Void set_Results(System.Collections.Generic.IEnumerable`1[Esri.ArcGISRuntime.Portal.ArcGISPortalGroup])
I was able to duplicate the problem with just the "Add a Map" tutorial. I thought it might be my old, 32-bit machine, but I tried it on a newer 64-bit machine with the same problem.
It works just fine, of course, if I don't try to compile with .NET Native tool chain.
Oh Sorry, I read too quickly your message and I missed the keyword 'native'.
For now the compilation with the .Net Native chain is not supported.
We'll investigate the possibility to support it for a future version. Though the ArcGIS runtime core components are already native (C++) so we can't expect much performance enhancements by using .Net Native.
I was able to compile and run the store SDK samples using VS2015 preview. So I guess you run into a specific issue.
Could you give more info about the line in your code that generated this compile error?