Help with Oculus VR (DX)- Can not access shared RenderTarget2D

[Warnestam]

I've just opened some of my old MG code and have been working on updating them from NET Framework 4.8 to .NET 6.0/7.0. Most of my old projects went smooth to update, but I have run into some trouble on a project that was using my Oculus headset.
My old code was based on a for long forgotten project, but I found som identical code on https://github.com/demonixis/C3DE

To get the Occulus headset working, there is a need to access the native textures for two render targets, This was done before with this code;

        public static IntPtr GetNativeDxResource(this RenderTarget2D renderTarget2D)
        {
            var renderTarget2DType = typeof(RenderTarget2D);
            var textureInfo = renderTarget2DType.GetField("_texture", System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.NonPublic);
            var resourceObj = textureInfo.GetValue(renderTarget2D);
            var resourceType = resourceObj.GetType();
            var resourcePtrInfo = resourceType.GetProperty("NativePointer", System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.Public);
            return (IntPtr)resourcePtrInfo.GetValue(resourceObj);
        }

After the upgrade this code created an exception, since the "_texture" was not found

But in the latest update (3.8.1.303) I found that this code could be simplified with;

public static IntPtr GetNativeDxResource(this RenderTarget2D renderTarget2D)
{
    var handle = renderTarget2D.GetSharedHandle();
    return handle;
}

Unfortunately the procedure was only returning IntPtr.Zero

To fix this, I changed the creation of the two render targets, forcing it to use shared memory

 var renderTarget = new RenderTarget2D(graphicsDevice, res.X, res.Y, false, surfaceFormat, depthFormat, 0, RenderTargetUsage.DiscardContents, shared: true);

Now I finally got the handle to the textures and hoped everything should work. But as soon as I submitted them to Oculus (via the same DLL I used a couple of years ago) I run into my latest problem

        public int SubmitRenderTargets(RenderTarget2D rtLeft, RenderTarget2D rtRight, int frame = 0)
        {
            IntPtr dxTexLeft = rtLeft.GetNativeDxResource();
            IntPtr dxTexRight = rtRight.GetNativeDxResource();

            return NativeRift.SubmitRenderTargets(dxTexLeft, dxTexRight, frame);
        }

The error: System.AccessViolationException: 'Attempted to read or write protected memory. This is often an indication that other memory is corrupt.'

I must have missed something but can not figure it out. Any help is welcome

Kind regards

Robert