I have the Harpy Trap diagram in my inventory and the enough materials to make atleast 1, but none of the crafters in the Chapter 2 city will allow me to craft it. It doesn't show up in the craft menu. There is atleast 1 other diagram i have that does the same thing. Is it a bug or...

This probably isn't helpful, but have you tried scrolling down on the craft menu?

Well this is a bit silly. I guess it fixed itself after relaunching the game