UPDATE: Ask Button problem has been resolved.
Upon entering Cafe World today, I saw a blurb at the top that said, "Hiya Chefs, we are aware of the “ask button”/ request issues in Café World. We are working hard to solve these issues quickly. Click here to report the issue ."
Asks that go to your wall DO work. This only affects asks where the friends list is supposed to pop up.
When it comes back, I'll let you all know. In the meantime, it's normal if you can't ask for something. Annoying, but normal.