An excerpt from Avraham Ben Yehuda here:
Question: The Chassidim say the Maggid paskened they can daven after chatsot is that lechatchila or bediavad?
Answer: The halacha as brought by the R’ma in Orah Hayim 89 is that it is forbidden to pray the morning service after noon, while the unstated opinion in disagreement would feel that shaharith in the afternoon would not count as anything. See the details here. Think about it. If one prays after noon, that’s minha, not shaharith. Real hasidim pray the morning service at sunrise.