For some reason the Binding qml type does not properly function when it is changing a binding of a QList<Bar> type (even when the metatype is registered). I've created a small project to demonstrate this issue. 

In the project, you can see that when you click the button, it properly goes through the recalcuating portion of the Binding type, but does not over change the value on the target like it is supposed to. In the code there are commented out sections, you can see that a normal binding does work (and properly puts out the changed signal for foo2's barList property, but when using any of the different forms of "Binding", this does not happen (meaning it never changes the property on foo2)

Qt 6.7 or later has the correct behavior.