You are right about Max von Sydow.  I think his performance is the best thing about the film.

I think that THE STENDHAL SYNDROME was so grim and depressing that it burned Argento out.  So, for his next film he did a tongue-in-cheek adaptation of THE PHANTOM OF THE OPERA.  The colossal failure of PHANTOM (& the death of the Italian film industry) left Argento adrift.

Don May said that issues with one of the talent is the reason that the commentary was dropped.  May wouldn't say who it was, but from what I've read elsewhere it seems the problem talent is Lustig.