THE GREAT WONDER- NO WONDER
The Mechaber in Shulchan Aruch (O. Ch. 580) lists additional fast days.
One of the fast days is on the 9th day in Teves. “It is unknown what
Tzoroh happened on that day”.
The ט"ז writes" תימה גדולה (It's a great wonder) that the Bais Yosef
doesn't know what happened that day. In our Selichos (Ezkero Motzok)
it is written that Ezra Hasofer died on the 9th of the month".
It is interesting, this Piyut is said, only by Ashkenazim. The Sefardim
say the Piyut “Sha’a Elyon” and the Piyut “Yoshev Bashomayim”.
In both of these Piyutim, it is mentioned that Ezra Hasofer died on the
10th of Teves.
The Mechaber, being Sefardi didn't say the Piyut Ezkero Motzok.
He said instead the other two Piyutim that states Ezra was niftar
on the 10th and therefore there shouldn't be a wonder why he
didn’t know what happened on the 9th of Teves. אמבצי