I'm having the same problem as the OP, with different families in different projects. Seems like there's always one mechanical equipment family that doesn't want to play nice with electrical connectors. Either the info in the connector won't report to the family or the info in the family (from the connector) won't report to the tag. The problem seems to be in the way Revit communicates the info from connector to the hard-coded Panel Name/Ckt # parameters in the family, and then from the family to the tag. Steve's solution of deleting the family and reloading it fixes the problem, but it's still frustrating.
I've had this happen to me before on my motor circuit schedule before using Mitsubishi fan coil units. I even tried the remove the families project and reload trick and it still didn't work. I asked this a while back but never got an answer for it so I suppose the contractors looked at my panel schedules and found them instead.