The 'em_impact_maint_ci' records are being created for CI's in Normal & Standard Changes and not for Emergency changes
There is a default maintenance rule called "CI in Change Window", that will add CI's to the em_impact_maint_ci table if the CI is in any active change window:
In order for the above rule to add CI's to the maintenance table, the change has to be in the 'state' of Scheduled, Implement, Work in Progress, or Open/New, and also the 'approval' field on the change should have the value as 'approved'
In certain cases, the emergency change workflow does not require approval, therefore the 'approval' field could remain in 'requested' state, and this does not satisfy the condition for the above rule.
Review the workflow for the emergency change process, and in order to include CI's associated with emergency changes in the Maintenance CI table, ensure that the 'approval' field is being set as 'approved'.