GH shows wrong original estimate even when there is no work clocked against main task or subtask of the main task

1. Main Task is created without defining original estimate. ABC-123
2. Add TWO Subtasks to the main Task and specify the original estimate - 8 hours each subtask.
3. JIRA output for the filter containing above three items is - Original estimate of ABC-123 = 16 hours.
4. Get the GH Excel sheet using Export to excel through chart board - Original estimate of ABC-123 = 0 hours.
5. On other hand with the same scenario Original estimate of ABC-567 = 40 hours.