Thank you for contacting Syncfusion support.
We would like to inform you that you can set ItemsSource to SfListView after items added into collection asynchronously in separate thread. Please refer the following code,
public class Page1 : ContentPage
private void processDataSubscribe(MvvmMessagePostThread dataMessage)
Device.BeginInvokeOnMainThread(async () =>
sflistView.ItemsSource = mainModel;
If reported issue still occurs, can you please check whether items fetched from DB in ListView loaded event. If no, please share the model sample so that we could analyze the reported query better and provide appropriate solution at our end.
Subburaj Pandian V