The 14th Amendment states that "All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States."
Did cases ever arise in courts concerning any ex-slaves not born in the United States include arguments that the 14th Amendment did not apply to them?
At least one such person was naturalized, according to Wikipedia, in 1868, a time at which I believe naturalization was conferred by district court judges. Although this doesn't perhaps constitute a court case, as asked by the question, it does show that formerly enslaved people who has been born outside the United States were not automatically granted US citizenship. Wikipedia says:
Although native-born American former slaves became citizens upon the passage of the Fourteenth Amendment to the United States Constitution in July 1868, this change in status did not apply to the members of the Clotilda group, who were foreign-born. Cudjo Kazoola Lewis became a naturalized American citizen on October 24, 1868.
The passage cites Dreams of Africa in Alabama: The Slave Ship Clotilda and the Story of the Last Africans Brought to America by Sylviane A. Diouf
Did cases ever arise in courts concerning any ex-slaves not born in the United States include arguments that the 14th Amendment did not apply to them?
As the answer from phoog notes, this did happen. But, it was very rare because international slave trade was made illegal under U.S. law many decades before the 14th Amendment was adopted and many decades before the U.S. Civil War.
