hire date change absences not appearing in plan

After hire date change, I am able to see the plans as is before and after the hire date. need below things:

1. Absence missing in the plan details section, I ran the evaluate absences but no use. still the absences not getting synced with the plan.
2. If I make any absence entry after the hire date change, those entries are appearing without any issue.
3. Update enrollment process not affecting the enrollment
4. calculate accrual process giving the accruals as expected.

What could be the reason that absences were not in sync with the plan, what is the solution: Do we need to delete the plan and re-enroll, which we don't want as some adjustments exist in the plan and is there any docs that show what is the impact of the hire date change on the absences?