While reading the comments for the Codecs article, I ran into an odd situation where I can't change the sort order of the comments, and also cannot expand lengthy comments to read the full.... uh... comment.
The Sort dropdown appears, but quickly decides that it wants no part of my mouse click and closes again with a flash.
Similarly, when I clicked to show the rest of a long comment, it displayed for a half second and then collapsed again.
NOTE: I do not have a Facebook account, nor am I interested in having one again.
UPDATE: Still happening. Running Mojave on a 2015 MBP, using Safari. Really? Nobody else? Weird!