In Microsoft Exchange Online for Microsoft Office 365, you apply a retention policy that moves email messages from a user’s mailbox to the archive mailbox. In this scenario, the retention policy does not automatically run.
The issue occurs because the retention policy runs automatically one time every 7 days for mailboxes that are larger than 10 MB. However, the retention policy does not automatically run for mailboxes that are smaller than 10 MB or within 7 days’ work cycle.
To resolve the issue, manually run Start-ManagedFolderAssistant –Identity <mailbox> cmdlet to force Managed Folder Assistant to process the specific mailbox in Exchange Online for Office 365.
//To resolve the issue, follow the steps:
1. Connect Windows PowerShell to cloud-based service.
2. Manually run Start-ManagedFolderAssistant –Identity <mailbox> cmdlet to force Managed Folder Assistant to process the specific mailbox.
Messages are not automatically moved to a user's archive mailbox after you create a retention policy in Exchange Online for Office 365
Set Up and Manage Retention Policies in Exchange Online
Connect Windows PowerShell to the Service
Office 365 Exchange Online
Well it very technical enough and supportive. I will try the steps and if fail will contact you.
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