I've relogged. I have the Provisions Mastery slotted on this toon. It's the only one on this account...
Annnd, got it - I was looking at options while outside WVW and the "Quick Interact" one was greyed out because I don't have the Advanced Logistics mastery yet. However, when I just looked while in WVW, it was available and that solved it.
Thanks for your input, which led to the solution.