The csproj file format has dramatically improved over the last years and you very likely needed to manually edit it.
However, there are lots of useful "dark magic" pieces of additional build logic and customization you can put in there (some of which you may have already copied from StackOverflow without understanding them).

Come to the dark side and learn how the MSBuild "programming language" works and the evil hacks you can then perform on your project and solution files (and also pack into a NuGet package!).

We'll also have a look at what tools to use for diagnostics when your build does not work as expected.