All user reviews for several films missing

Hi,

Following on from my previous post about many reviews of mine being missing, I saw on another thread a comment saying that several films had all their user reviews missing. I investigated further, thinking that it would explain why I had a significantly lower volume of reviews. And I found that quite a lot of film titles, most of them silent films, had all their user reviews missing. Examples of the films in question being The Lodger, Faust, Nosferatu, Birth of a Nation, Intolerance, in fact most of the filmographies for the likes of DW Griffith and FW Murnau. Is there a reason for this

Thank you.