SOLVED: can't find existing collections / add movies in them

[siro]

Thanks, it works!
It's tricky, indeed I didn't select the "Collection" view to be displayed for my user, because I want each collection to be displayed directly within their media view (like Films, Anime, ...) and I don't have an interest in getting all collections grouped in one view.
So I have added the collection view for the user and now the collections are visible when in the panel to add an item to a collection.