Associated Press. The two lawyers at a big New York law firm who were working on a capital defense matter had moved on to other jobs and so the court notice sent to the firm was returned to sender. The deadline was missed.
At some firms, the mail is opened by a professional staff person who knows what to do with court notices, even if the attorneys on the matter have moved on. (In such firms, the mail staff would already know that the two lawyers had left and that their mail had to be treated differently.) And some firms have systematic ways of identifying all the matters that departed lawyers were handling and then sending proper notice out. The case being heard by the SCOTUS is more complicated, because local counsel apparently knew of the deadline and just assumed that the two lawyers at the big New York firm were responding to the deadline.