Item ID: 6512 (https://bddatabase.net/us/theme/6512/)
Description: When you talk to Cruhorn Wyrmsbane (In Heidel, training grounds), you get the option to learn the knowledge “Two Faces of Calpheon”. However, when you click on the knowledge, you do not unlock it, and it stays locked.
Proof: See at the bottom of the file report.
Family name: Dawnmyre
MC name: Dyn
Discord name: Syl#8749
Proof: (Knowledge locked)