Components are not recognized

Several components are not recognized on Qt Creator even though the code works. For instance add following code 

import Qt3D.Core 2.0

Entity {
    Transform {
    }

    NodeInstantiator {
    }

    Component3D {
    }
}

Transform, NodeInstantiator and Component3D have a red line and they give error "unknown component. (m300)". Sometimes after waiting a long time they get recognized.