Same problem as described here:
gog.com/forum/the_witcher_3_wild_hunt/cat_school_gear_boots_diagram_problem
No idea how that "solution" is supposed to help.

Edit:
I dowloaded the Debug Console enabler and cheated me a copy of those diagramms, I still can't complete that quest but at least it won't keep me from the grandmaster gear.

Edit2:
Aww well, qust terminated itself after I picked up the sword upgrade diagramm.