Project format changed. Now files in the directory are automatically included in project - this make Modlr not find them in project file and codegen has become sktechy.

Add this to Project

  <EnableDefaultCompileItems>false</EnableDefaultCompileItems>
</PropertyGroup>

Also make sure you have this dependency on files:

<Compile Update="EcoProject1\Class3.eco.cs">
  <DependentUpon>Class3.cs</DependentUpon>
</Compile>

This should be fixed in FW..