Code Generation Not Working for One or Several Classes

The project file in Visual Studio should have dependencies defined:

<Compile Include="EcoProject1\Class1.cs" />
   <Compile Include="EcoProject1\Class1.eco.cs">
     <DependentUpon>Class1.cs</DependentUpon>
</Compile>

If this structure isn't correct, for example, due to a merge error in source control, do this to correct it:

1. Exclude (not delete!) all the generated class code files, both the .cs and the .eco.cs files.
2. Code-generate everything again with "Ctrl + <the C# button>"

No files will be overwritten, but the correct VS structure will be regenerated.

See also: Codegen failed, Codegen Issues .net standard