Azure Backup now supports BEK encrypted Azure virtual machines
Updated: 10 April, 2018
Azure Backup now supports backup and restore of Azure virtual machines encrypted using Bitlocker Encryption Key(BEK) for managed or unmanaged disks. This announcement augments the existing capability to backup VMs encrypted using Bitlocker Encryption Key(BEK) and Key Encryption Key(KEK). This support is available using Portal and PowerShell.
For more details, read this post.