How to update contract end date using import management?

Summary:

I am trying to update contract end date for an active contract using Import Management. The import is successful, but the changes not reflected.

Content (please ensure you mask any confidential information):

Since it is only for update, the file that I upload only contains of these details: PU ID and Contract End Date with Options of Object: Contract, Import Mode: Update and create records, Date Format: UK/Canada-DD/MM/YYYY

Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):