I'm on desktop, Chrome browser, no adblock and clicking on add note does nothing. No note appears to move around, it doesn't move me to the top of the page or anything. Inspecting the link there doesn't appear to be anything for the link to do:

<a id="translate" data-shortcut="n" href="#" title="Shortcut is n">Add Note</a>

I noticed this yesterday when I tried to add the translation notes to the below image, but I've tried other images since and the same thing happens.

gelbooru.com/index.php?page=post&s=view&id=5835475

Hover over image, click and drag a rectangle after clicking add note.

Thanks, that's not at all obvious since it was totally different before.