Hi ,
Its easy to solve when we know your current Hybrid Model . I can solve this issue over screen share .
I am seeing there is configuration issue with connector and centralize mallow . when we have coexistence setup and your MX is configured with Office365 and mail will be delivered directly to your EOP and then from EOP it route mails to destination .
I am certified Microsoft 365 Solution Consultant and responsible for managing and designing Cloud and Infrastructure platform. Expertise in Microsoft 365 Messaging, Security & Compliance, Exchange, Teams, SharePoint, MDM, Windows Server, Active Directory.
Regards
Sumit