Comments missing, disappeare only at one post! Where have all the comments gone?

https://human-stupidity.com/stupid-dogma/racial-differences-intelligence/race-differences-in-intelligence-how-i-changed-my-mind/comment-page-2#comment-15597

This is the post with the most comments. Until recently, comments did show.

Comments also show in the comment admin section. Looking at the source version of the page in questions, It seems it is not a formatting fluke, rather they are really gone in the html.

Comments at other posts are still there
https://human-stupidity.com/stupid-dogma/teenage-sexuality/change_org-sucks-censors-anti-feminist-dissent/comment-page-1#comment-15460

Off topic: how can I get a post with many comments to paginate them with something like “more” <–more–> ?