Support for VMs with disk storage located on SMB 3.0 shares was recently introduced. Please ensure your DPU is on the latest version of RecoveryOS and that the Hyper-v Agents are on agent 8.0 or greater (preferably, the latest).
For more details, review the Administrator Guide for Recovery Series and Unitrends Backup, Chapter 6: Host-level Backups Overview > Hyper-V virtual machines, > Best practices and requirements for Hyper-V protection > Additional Hyper-V requirements, in the listed chart, under the Item called Storage on SMB 3.0 shares. Ensure that any Firewalls have been updated to allow the transfer of information given the protocols needed between the systems involved in the data and information exchange.
Please be aware of this known where a Hyper-V 2012 host crashes on backup or guest migration if the Hyper-v host has VMs with disks residing on SMB3 shares. KB 4442 describes the details requiring you will need to remove the Hyper-V CBT driver from the Hyper-V hosts and replace the CBT tracking functions with the Unitrends hash scanning Hyper-V incremental process.