In January 1944 A Daas Torah was given in Hungary that Jews should stay in Hungary rather than leave.
In April 1944 Admiral Horthy was overthrown and the gavel of Auschwitz fell on the Jews of Hungary
I’m not sure why this is relevant. There was no way for Da’as Torah to know the future, as they are not Omniscient. As such, they reasonably believed the people were safe (which they weren’t).
Alternatively, understanding that the Holocaust was a Gezairah Min HaShomayim, Hashem blocked the “Einei HaEidah” from seeing what the potential danger was, as part of His master plan that needed the Holocaust (and all of the deaths) to happen.