That's exactly where you are wrong. Here is the question as written by the Court in Minor.
The question is presented in this case, whether, since the adoption of the fourteenth amendment, a woman, who is a citizen of the United States and of the State of Missouri, is a voter in that State, notwithstanding the provision of the constitution and laws of the State, which confine the right of suffrage to men alone. (...) The argument is, that as a woman, born or naturalized in the United States and subject to the jurisdiction thereof, is a citizen of the United States and of the State in which she resides, she has the right of suffrage as one of the privileges and immunities of her citizenship, which the State cannot by its laws or constitution abridge.The plaintiff's whole argument is that Minor as a citizen of the U.S. had the right to vote. The Court agreed that she was a citizen but disagreed that such citizenship gave her the right to vote.
You are simply wrong on the face of your argument that her citizenship was not a question presented to the Court. The Court tells us in black and white that it was part of the question being decided because it was the basis of the plaintiff's argument.
I am sorry if you can’t understand the difference in a court of law.
Is Person “A” a citizen?
Versus
Does the sex of Person “A” preclude her from voting when she is a citizen.
The second question is what was before the court.
NO ONE DISPUTED THE MINOR WAS A CITIZEN.
Fact not in dispute.
The whole question before the Supreme Court was whether the 14th Amendment allowed for Suffrage.
HOLDING - NO.
The holding was not that she was a citizen. EVERYONE AGREED SHE WAS A CITIZEN.
The HOLDING was NO SUFFRAGE.