After migration, users can see that the sensitivity label has been successfully applied to migrated items. However, the expected actions associated with the label, such as encryption, protection, access restrictions, watermarking, or other policy-based behaviors, are not applied.
It's not supported by ODM.
This is expected behaviour.
ODM migrates and applies sensitivity labels to supported items but does not process or enforce any actions associated with those labels. Label actions and policies are managed by Microsoft 365 services and are not triggered by ODM during migration.
As a result, while the label itself is present on the migrated item, any behaviour configured within the label is not executed by ODM.