It was a short and it did involve the EZ track connectors
The cords for the switch machines also go either way. You might switch it to diverging and nothing happens, but when you switch it to main it goes to diverging. The remedy is the same: flip over the plug. Take a piece of tape and mark the "up" side.
One thing that I like about Kato products is their "idiot proof" construction. Many Kato products only go together one way.