Using reflection in net core packages targeting several frameworks

I am developing a library(nupkg) in .net core targeting both net45 and netstandard1.3 and at some point I need to use reflection so my project.json looks like this:

{
  "version": "1.1.3",
  "dependencies": {
       common-dependencies
    }
  },
  "frameworks": {
    "net45": {
      "frameworkAssemblies": {
        "System.Reflection": "4.0.0.0"
      },
      "dependencies": {
        "NLog": "4.3.5",
        "Newtonsoft.Json": "6.0.4"
      }
    },
    "netstandard1.3": {
      "imports": "dnxcore50",
      "dependencies": {
        "NETStandard.Library": "1.6.0",
        "System.Reflection.TypeExtensions": "4.1.0",
        "Newtonsoft.Json": "8.0.2",
        "NLog": "4.4.0-*"
      }
    }
  }
}

Most of the times after a mere install-package my-package everything works like a charm, however a couple of times I get this error on installing:

install-package : Failed to add reference. The package 'my-Package' tried to add a framework reference to 'System.Reflection' which was not found in the GAC. This is possibly a bug in the package. Please contact the package owners for assistance.

I've found a workaround, which is to uninstall-package every other package on the project I want to install my package. This is very odd and undesired behavior I think.

I do have noticed however that on some of those project had different versions of Newtonsoft.Json installed on different projects. This is a warning I also get when installation fails:

Install failed. Rolling back...
Package 'my-package : Newtonsoft.Json [6.0.4, ), NLog [4.3.5, )' does not exist in project 'Target.Project'

I have no idea what could be going on here, and the fact that it happens randomly and the workaround to fix it don't help much.

Any ideas please?