It seems like they went backwards from the 1875 14th amendment decision. How did they justify it and what really caused this to happen?
You missed the 1873 Slaughterhouse Cases, which found that the 14th Amendment didn't really mean what the writer said it meant.
The Slaughterhouse cases (83 U.S. 36 (1873)) held the fundamental rights protected against federal abuse (first 10 Amendments) are not privileges or immunities of national citizenship within the meaning of the Fourteenth Amendment; nor are such other basic rights as the right to live, work, and eat. Thus, the guarantees of the Bill of Rights are protected from state action only by the Due Process and Equal Protection Clauses of the Fourteenth Amendment.
Also, it would help if you named cases rather than dates.