Loading Windows 10 DLL. "This operation is only valid in the context of an app container"

I am currently working on a native plugin for Unity involving other static libraries (dependencies). I have recently upgraded to Windows 10, and am running the most current Unity. I followed instructions and dropped my dll in the Plugin’s folder within Assets, but when running in editor I get the error in the title. The dll fails to load and subsequent calls to imported methods gives me "file not found ". Here is my local c# referencing the dll:
public class video : MonoBehaviour {
public string videoName;
public string folder;
public bool isPlaying;
[Range(0.0f, 100.0f)]
public float videoTime;

    public delegate void FrameCallback(int id, IntPtr data, int width, int height);
    public FrameCallback frameHandler;

    [DllImport("ffmpegForUnity")]
    public static extern int initVideo(string name, string folder);
    [DllImport("ffmpegForUnity")]
    public static extern int setFrameCallback(FrameCallback fn);
    [DllImport("ffmpegForUnity")]
    public static extern void getVideoFrame();

    public struct Frame
    {
        public int id;
        public byte[] data;
        public int width;
        public int height;
    }
    Frame mFrame;

    // Use this for initialization
    void Start () {
        //set up video context
       initVideo(videoName, folder);
        frameHandler = new FrameCallback(FrameHandler);
        setFrameCallback(frameHandler);
	}

and the header file for my dll:

#ifdef FFMPEGFORUNITY_EXPORTS
#define FFMPEGFORUNITY_API __declspec(dllexport)
#else
#define FFMPEGFORUNITY_API __declspec(dllimport)
#endif

extern "C"
{
#include <libavcodec/avcodec.h>
#include <libavFormat/avformat.h>
#include <libswscale/swscale.h>
#include <libavutil/avutil.h>
}

using FrameCallback = void(*)(int id, uint8_t* data, int width, int height);
FrameCallback mFrameCallback = NULL;

namespace ffmpegForUnity {
	class  videoHandler {
		
		public:
			static FFMPEGFORUNITY_API int initVideo(char* video, char* folder);
			static FFMPEGFORUNITY_API void* getVideoFrame();
			static FFMPEGFORUNITY_API bool setFrameCallback(FrameCallback callbackMethod);
	};
}

Has anyone run into this before? Googling has not helped. I found one other problem and the solution was to run the unity application in a visual studio simulator, but I want my plugin to be able to be used on multiple platforms, not just in the windows store.

Hey,
Your library was probably compiled for Universal Windows Platform. Libraries compiled for Windows Universal won’t run on native Win32 or the editor, giving you the error “This operation is only valid in the context of an app container.”