Components become invisible to the QML engine when applying QT_DISCARD_FILE_CONTENTS option to the QML source files:

set_source_files_properties(
       main.qml
    PROPERTIES
        QT_DISCARD_FILE_CONTENTS TRUE
)

qt_add_resources(appmulti-module "main_qml"
    PREFIX "/"
    FILES main.qml
) 

Running the application ends up with an error:

QQmlApplicationEngine failed to load component
qrc:/main.qml: File is empty

Since Qt 6.10, qt_add_resources() introduces the new option DISCARD_FILE_CONTENTS, which does not work either.

This issue does not occur when using qt_add_qml_module() function with the DISCARD_QML_CONTENTS option. But if we define multiple QML modules in a single CMakeLists.txt, there will be a similar problem.

The attachment contains a minimum reproduce project.