For any Deferral issues first research, but the deferral is still calculating interest after the 180 grace period.  

1. Check the control table to see if BoolCalcDeferraldaily  is set to 1, if set to one change to = 0.

2,  Check the featureflag table in SQL.  see if UseNewCalcRoutine is set to 1, if not set it to one.