C# Localization - multiple resx files but only one working aside from default

Question

I have a simple console application (.NET Framework 4.6.1) where I'm trying to use multiple resx files by changing cultureinfo. Here is my code:

       `static void Main( string[] args )
    {
        //default
        Console.WriteLine( Resource.Hello );

        Thread.CurrentThread.CurrentCulture = new CultureInfo( "fr-FR" );
        Thread.CurrentThread.CurrentUICulture = new CultureInfo( "fr-FR" );

        //french
        Console.WriteLine( Resource.Hello );

        Thread.CurrentThread.CurrentCulture = new CultureInfo( "hu-HU" );
        Thread.CurrentThread.CurrentUICulture = new CultureInfo( "hu-HU" );

        //hungarian
        Console.WriteLine( Resource.Hello );
        string res = Resource.ResourceManager.GetString( "Hello", CultureInfo.GetCultureInfo( "hu-HU" ) );
        Console.WriteLine( res );

        Console.ReadKey();
    }`

My default culture is en-US. I have a single line in the resx files with the key "Hello". For some reason with fr-FR cultureinfo it works fine but the others got the fallback value.

Related part of the project csproj file:

<ItemGroup>
  <EmbeddedResource Include="Properties\Resource.hu-HU.resx">
      <DependentUpon>Resource.resx</DependentUpon>
  </EmbeddedResource>
  <EmbeddedResource Include="Properties\Resource.fr-FR.resx">
      <DependentUpon>Resource.resx</DependentUpon>
  </EmbeddedResource>
  <EmbeddedResource Include="Properties\Resource.resx">
    <Generator>ResXFileCodeGenerator</Generator>
    <LastGenOutput>Resource.Designer.cs</LastGenOutput>
</ItemGroup>

I added all the resx files manually to my project and under Properties. Only the default has a designer.cs

Any ideas? Thanks for advance!