CMake: Files added through project configuration are not found immediately

1. Git clone https://github.com/llvm/llvm-project.git
2. Open llvm/CMakeLists.txt and configure the project (wait until it finished)
3. In Projects mode, set LLVM_ENABLE_PROJECTS to "clang;clang-tools-extra"
4. Hit "Apply Configuration Changes"
5. In the locator, type "clangd" to find ClangdMain.cpp --> Ops, nothing.
6. Hit "Apply Configuration Changes" again --> Ops, shouldn't it be grayed out?
7. In the locator, type "clangd" again --> Ops, nothing.
8. Close the project and re-open it.
9. In the locator, type "clangd" again --> Aha, found.

Note that by setting LLVM_ENABLE_PROJECTS more sub projects are included.