Ghostery was blocking site elements. I don't know quite what to think about it. I haven't run into many sites that are so thoroughly broken by the things that Ghostery blocks. (Basically, in most cases, the main content of a site is hosted on the site's own servers, and things like ads, trackers, etc. come from a third party's servers, which is how ad blockers can recognize them and block them without blocking the whole site. So, major portions of LJ's user interface are coming from a separate domain than the content. I'm not an expert, but that seems very weird to me.)

Unfortunately I'm having trouble remembering whether I've tried to do any of the stuff that was blocked since I installed Ghostery. It was awhile ago--probably about a year? I guess it's possible I just haven't tried to do these things in the last year and I'm only now noticing. Or maybe parts of the interface got shifted to different domains in the move? I don't know.