Benefits plan rate dropping to 0 when default enrollment fast formula type is used

Summary:

We are having a Benefits plan with different options and a Default Enrollment type fast formula is attached to the plan.  This fast formula is used to determine whether an option in plan should be assigned to a person as part of the default enrollment process and therefore returns only two variables AUTO_DFLT_VAL as 'Y' or 'N' and CARRY_FORWARD_ELIG_DPNT as 'CFRRWP' and 'CFWP'. However, when the same plan and option is retained upon loss of eligibility life event trigger, the rate also drops to 0. But we want to retain the same rate as usual with the same plan option