After synchronisation, existing JIRA ticket label which is not available as tag in cucumber scenario is not deleted

Normally, after a synchronisation of cucumber feature file with JIRA PT ticket, we expect only the tags mentioned in the cucumber feature file to be added as labels in the PT ticket. Any additional labels in the PT ticket should be removed. This is how it used to work.
However, recently, the labels defined on a PT ticket, which are not added as a tag in the cucumber feature, are not deleted as part of the synchronization job.
Summary :- The tags defined in the cucumber feature are added as labels. However the unwanted labels which are not defined in the cucumber feature are not deleted.