Steps to reproduce

1. In Qt Design Studio, create a new project
2. Load the top-level CMakeLists.txt in Qt Creator
3. Open content/App.qml in the code editor

(As an alternative to Steps #1 and #2, you could also create a new "Qt Quick Application" in Qt Creator and enable "Creates a project that you can open in Qt Design Studio")

Outcomes
Qt Creator says, "QML module not found"

Workaround
In the top-level CMakeLists.txt, add the following:

set(QT_QML_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/qml)
set(QML_IMPORT_PATH ${QT_QML_OUTPUT_DIRECTORY}
    CACHE STRING "Import paths for Qt Creator's code model"
    FORCE
)

Notes

• ${CMAKE_BINARY_DIR}/qml is used above for compatibility with the template which is enabled when -DBUILD_QDS_COMPONENTS=ON : https://github.com/qt-creator/qt-creator/blob/v12.0.0/share/qtcreator/qmldesigner/studio_templates/projects/common/qmlcomponents.tpl#L6