I´ve been experimenting, but I don´t know PhP so:
I´ve hacked template-functions-post.php, and I´ve replaced <a id="more-'.$id.'"></a>'.$content[1]; by <a href="'. get_permalink() . "#more-$id\">$more_link_text</a>"; and now woks, but the entry extended display more_link_text 🙁
I don´t know why happens this, because on the other wp installation I´ve <a id="more-'.$id.'"></a>'.$content[1]; and works 😕
<p><a id="more-5"></a><br />
I’ve made 2 installations of wp in the same server, one have same problem and I don’t know why…
