Warning NU1701: package build for Core2.0 is being restored with .NET4.6.1 in a .NETCore2.0 app

I have build my own nuget package containing a dll build for the .NETCore2.0 framework.

<PropertyGroup>
      <TargetFramework>netcoreapp2.0</TargetFramework>
      <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
      <Authors>xxx</Authors>
      <Company>xxx</Company>
      <Product>xxx</Product>
      <AssemblyName>App.Model.Master.Contract</AssemblyName>
      <RootNamespace>App.V4.Model.Master.Contract</RootNamespace>
    </PropertyGroup>

I am now trying to import this nuget in another project (MVC dotnetcore 2.0), and I am getting this error:

Package 'App.Model.Master.Contract 1.0.0' was restored using '.NETFramework,Version=v4.6.1' instead of the project target framework '.NETCoreApp,Version=v2.0'. This package may not be fully compatible with your project.

Those both project are using .NET Core 2.0. At no point I am using the classical .NET Framework 4.6.1. Why does it attempt to restore this package using this version of the .NET Framework?

Obviously I am missing something, but I am very confused on what is triggering this error.