Unable to delete assignment with TERMINATION action

Summary

Unable to delete assignment with TERMINATION action. Error message 'You can't delete the WorkTerms record with effective start date 2020-01-01 because a corresponding Termination record exists.'

Content

The current assignment is :

Effective Start Date - Effective End Date - Action Code      - Effective Sequence - Effective Latest Change

2020/01/01              - 2020/01/01             - TERMINATION - 1                              - N

2020/01/01              - 4712/12/31             - TERMINATION - 2                              - Y

And below is the command that I use to merge the record:

SET PURGE_FUTURE_CHANGES Y
METADATA|WorkTerms|AssignmentId(SourceSystemId)|PeriodOfServiceId(SourceSystemId)|ActionCode|EffectiveStartDate|EffectiveEndDate|EffectiveSequence|EffectiveLatestChange|ReasonCode|AssignmentStatusTypeCode
MERGE|WorkTerms|WT1|PPOS1|RETIREMENT|2020/01/01|4712/12/31|1|Y|CT_NRML_RTR|INACTIVE_PROCESS