I finally used up all my kudoes

[Angrboda]

I don't think it's lag, if I don't leave the thread, it doesn't update (from my point of view) even after 15 minutes, but leave the thread (or do something like delete my alerts) and come back, and there they are.

Sounds like a browser problem. Things like kudos'ing and quick editing don't fetch a new page, I don't know exactly how they work, but they're akin to a script running on a page and that script updating things (I think), so if that script doesn't finish, or your browser doesn't re-render the page, the kudos won't show up. Try a different browser and see if you get the same result.