Student groups, effective dating, and academic advising

Our registrar's office is reporting a problem with student groups and academic advising.  It appears that when students have been assigned more than one group, the academic advising report ignores groups with earlier effective dates.

For example, a student is assigned to the group FRSH, effective dated  09/15/14.  The FRSH group is used for academic advising.  Later the student is added to another, non-advising group, HPME, effective dated 10/09/14.

When the academic advising report is run it seems to ignore the FRSH group, so the academic advising report does not work properly.  Is there a possibility that the more recent effective date could be interfering with the earlier student group assignment?