I have a document which is visible in a view: View1
In another form I have a subform which has an embedded view with a embedded selection to View1.
Now this document is not visible in this embedded view how come? I do also have other documents and those documents are visible.
Are you looking at the view on the same server that the embedded view is accessing? If not, that's your problem. Is the view categorized? Is the embedded view set to show a single category? If it is, that's probably your answer right there
Otherwise, you need to update your question with additional information. We need to know more about what you are doing, about that view, and about the document.