Errorplan has been doing this for a long time, it's their way of stinging you for the full cost of a J redemption and not living up to their end of the deal. Sadly, most people don't notice, and only find out they're stuck in Y after they board the plane. By then of course, it's far too late.
Sleazy? You bet. But it's been standard operating procedure for years.
Try booking a two one-way trips, as rankourabu suggests ... you never know.