upload component does not work from application embedded in page via div

Hello,
upload component does not work from application embedded in HTML page via div tag (as per Vaadin book 11.3.1 - Embedding inside div element ) - no listener is called.

My question is - Is using embedded application recommended for production use?
e.g. Resource download does not work either - see my post
https://vaadin.com/forum/-/message_boards/view_message/874982

Any Idea?
Any workaround?

Thank you,
Jan