Hi team,
This has been discussed previously: https://community.hubspot.com/t5/Outlook-Sales-Extension/Assigning-Contact-Owners-When-Multiple-Users-are-Syncing-Outlook/td-p/1118880
Contacts are created/synced from Outlook without an owner.
Portals with multiple users syncing hundreds of contacts from Outlook cannot identify ownership or easily bulk-update the Contact Owner property.