Unfortunately Phenix does not always treat labels the same between different reflection file formats.  In MTZ files there is a strict correspondence between "column labels" and what you see in the various programs in Phenix, so anomalous intensities with sigmas will always appear as something like "I(+),SIGI(+),I(-),SIGI(-)".  Scalepack files will always appear as "i_obs,sigma" whether or not they contain anomalous data.