To clarify, is this a feature request, or do you believe the timestamp you passed was saved incorrectly?
If this is a feature request, could you create a post on the HubSpot Community Ideas Forum per these best practices? This information is sent directly to our Product team and helps prioritize feature requests that have the greatest impact on our customers.
If you believe the timestamp you passed was saved incorrectly, could you share your test portal ID and the request body you used to create the post with the correct timestamp?