Header-only libs and VStudio Generator?

Usage
1

i’ve tried to add a header-only lib project to my VStudio 2017
using latest CMake Release 3.20.5 under Win7 x64 in a x64 C++ Projekt

using the tutorial here:
http://mariobadr.com/creating-a-header-only-library-with-cmake.html

my CMakeLists.txt works - no errors etc. but it seems that no Studio project
gets generated

according to Issues (18491, 18608) there were some problems - but all seem to be fixed

still, i don’t see a project for my lib in VStudio, nor is anything generated

is there a small working example around or are there still open issues to fix to get that working?

Hierarchy:

this tryout generates a project but the add_custom_target seems not to be clear/pure CMake style

cmake_header_only_dev\__build
cmake_header_only_dev\cmake_header_only
cmake_header_only_dev\cmake_header_only\CMakeLists.txt
  cmake_minimum_required (VERSION 3.19)
  project (my_header_only_lib)
  add_subdirectory (header_only)
      
cmake_header_only_dev\cmake_header_only\header_only
cmake_header_only_dev\cmake_header_only\header_only\CMakeLists.txt
  #target_sources(header_only INTERFACE test.hpp)
  if(MSVC)
    add_custom_target(header_only SOURCES test.hpp)
  endif()
  #add_library(header_only INTERFACE)

cmake_header_only_dev\cmake_header_only\header_only\test.hpp