HubSpot
Date fields
Using API v3, For a date only field, you need to explicitly set the date to midnight UTC
Function ScriptedField ScriptedField=FormatDate("@@ORG:date_entered@@", "yyyy-MM-ddT00:00:00Z") End Function
Updating Contacts
When updating contacts, if you are matching on email address, you must be sure NOT to pass in a blank email address. HubSpot will not know which contact to update and will update a random contact with incorrect data. You can either exclude blank emails from your origin or check the "Skip if Blank" checkbox on the email address field. I prefer to do both.