With curses being broken against other players but working fine with self cursing, I was wondering if this was intended, a bug, or just being ignored.

"An' I'm learnin' 'ere in London what the ten-year soldier tells; If you've 'eard the East a-callin', you won't never 'eed naught else. No! you won't 'eed nothin' else"

I've had no trouble cursing other players.

So, to quote Ryan Reynolds, "what?"