Not sure yet whether it's a display bug or a 'bug' bug, but I currently seem to be unable to place 'margin funding' offers.
I enter the details and click the button and it says "Offer placed" but nothing shows up in the "Unfilled offers" area. Also nothing visible on bfxdata.
Oddly though, if I click "cancel all", the first time it says "All offers cancelled", but subsequent times, "No offers to cancel", as if there was something there the first time.
Edit: Scratch that, it just took a long-ass time to appear in the Unfilled Offers list.
I haven't yet tried their api in respect to funding, but it is a big pain in the ass even to manually put simple buy-sell orders in the trading section, while through api everything works like a charm (though the api itself is a hell on its own)...