There has been a bug on Bitfinex for months that allows making naked margin trades (ZERO swap payments since you don't need to borrow anything!) and opening limit orders that are impossible to fill - they just vanish if someone tries to trade into them.

Incidentally, lenders, this is likely why you have been getting stiffed recently.

Want to know how? It's simple! Just open the margin trading tab, hit the blue "margin available" button, then set the maximum margin rate to something impossibly low - maybe 0.01%. Now you can trade without any of those annoying swap payments. If you want to open fake limit orders that cannot fill, uncheck "include variable rates?" and you're in business.