How did you temper them? Each most likely has its own tempering profile: "...milk fat delays the onset of crystallisation, lowers the melting point of cocoa butter and that chocolate containing milk fat requires lower temperatures and longer times for tempering." source
We are using a Selmi Futura tempering machine. We temper between 84.2 and 86 degrees fahrenheit. Our room temp is about 64 degrees and our cooler is at 58 degrees.