Look close to see that no wheels sit narrow in gauge. If the backside rubs the wrong spot on a center rail, you may short. Also check that no roller is hitting the top of two rails in the turnouts. Wide rollers or tilted vs level rollers can short on turnout rail tops. (Sometimes the boss where the roller axle is can hit too)
I also wonder if you have insulated the antiderail with fiber pins as(if) needed