This is due to the deployment model setup of the Azure Storage with the Resource Managed deployment model
When the block blobs are uploaded to Azure, Microsoft accesses in order to upload from the storage container to SPO
1) Provision a new Azure Storage for Classic deployment model [The SharePoint Online Migration Considerations for Maximum Performance.pdf which comes in the download recommends to setup using the Classic Deployment model]
2) The resource manager has restrictions being blocked from Microsoft [so once those IPs are received and implemented in the firewall to allow the Resource manager deployment model would also work] For this IP range, it would be needed to contact Microsoft. {please note however that not all Resource Managed storage models have been tested however General Purpose V1 and V2 could be considered]
