Can't change secondary profession

[Milaton]

As the title describes, in spite of running a factions character and having completed the weh no su- related mission as well as the ascent in prophesies, I can't change my secondary profession for some reason. It's just greyed out as if I hadn't gotten far enough to do so, even though I already killed shiro in factions.

[Doxorn]

In Factions and Nightfall you have to buy each secondary profession once to unlock them. Each costs 500gold to unlock first then you can freely change them.

In Factions you go to "Senji's Corner" and speak to Senji [Profession Changer]
In Nightfall you go to "Command Post" and speak to Zuwarah [Profession Changer]