13.1 Implement Methods... does not work with new interface method that looks like old interface method

Hey,

I notice an issue with IDEA 13.1 (135.475) Ultimate.  I'll clarify.

I'm implementing an interface that already has an implemented method with signature "public boolean deletePaymentSnapShot(PaymentSnapShot snapShot)".

The new interface method has signature: "public boolean deletePaymentSnapShot(PaymentIdentifierType identifier)".

So, I went to the implementation class and pressed "Alt-Insert" and then selected "Implement Methods...". IDEA correctly shows me the only unimplemented method in the dialog (and compilation also fails correctly).  But when I select that method and press "OK", absolutely nothing happens.

If I comment out the old existing method in the implementation, 'Implement Methods..." works correctly.