Windows 10 UWP Store app using CUDA - does it work?

I have an existing windows store app, written in C# with C++ libraries to do the hard work. I’m trying to replace some of the more intensive maths with CUDA but I’m struggling to even get the basics working. The closest I can get is to create C++ UWP DLL project then manually modify it so it has the “CUDA C/C++” and “CUDA linker” property pages. Then copy over all the library and path references from one of the sample projects. This eventually builds and I can reference it from by C# project. I have a couple of simple function to test it, first a version check
int version;
cudaError_t err = cudaDriverGetVersion(&version);
which gives a version of 9020 and err 0

then
int GPU_N;
err = cudaGetDeviceCount(&GPU_N);
which giver err = 30 Unknown error

Has anyone got further than this?

Any help could save the last of my hair and possibly my sanity!