Layout issue while using Loader

[jaquilio]

I have a layout arranged as follows

Rectangle {
        id: rectSide
        width: 400
        height: 500

        ColumnLayout {
            anchors.fill: parent
           ... some elements...
            Loader {
                id: loaderMyComp
                Layout.fillWidth: true
                Layout.fillHeight: true
                source: "MyComponent.ui.qml"
            }
        }
    }

With the use of the Loader as above, "MyComponent" doesn't look right at all and has several issues such as (1) Not occupying the full width of the rectangle in spite of Layout.fillWidth: true. (2) Some parts of "MyComponent" don't even appear.

Instead, if I modify the code not to use the Loader and instead directly add "MyComponent" to the layout as shown below, it works right.

Why is that? Why doesn't the layout work right while using the Loader element?

Code that works:

Rectangle {
        id: rectSide
        width: 400
        height: 500

        ColumnLayout {
            anchors.fill: parent
           ... some elements...
            MyComponent  {
                id: myComp
                Layout.fillWidth: true
                Layout.fillHeight: true
            }
        }
    }