My default comment sort was ‘old’ as well. I’m continuing to discover OS/browser variability: On my Android phone, Firefox-based browser (Mull) has no comments, but chrome-based (Kiwi) does. Under MacOS, all browsers except Arc display comments properly. On Manjaro linux, firefox no, chrome-based yes.

[edit] Changed sort on Arc Browser under MacOS and, indeed, comments now appear–but I was unable to edit this there. Had to open Vivaldi. Odd.