I was trading with a number of other regions in Vix successfully - but perhaps some of our regions were over the line, I'm not sure. Strange that I could set up the sell offers but then not see them afterwards though, but perhaps that is intentional.
"Intentional" might be a bit of a strong word, but after looking at it for a while, we've decided it's not exactly a bug, either.
There's some clarifying text coming the next time we send an update live (which should
hopefully be soon, but I won't promise anything...).