After applying patch 1 for 22.214.171.124 you are no longer able to backup or replicate Hyper-V virtual machines, jobs fail with the "Unknown drive type [ISO]" error. The following entries can be seen in the job log:
[timestamp] <01> Error at Veeam.Backup.Core.CHvVmConfigFile.ParseDrive(XmlNode node)
[timestamp] <01> Error at Veeam.Backup.Core.CHvVmConfigFile.ParseController(XmlNode node, Int32 controllerNum)
[timestamp] <01> Error Unknown drive type [ISO] at Veeam.Backup.Core.CHVVMCfgDrive.ConvertStringToType(String typeStr)
XML files of the backed up virtual machines are not parsable, when Hyper-V host with non-English locale is used.
The issue will be fixed in version 6.5, as a workaround change the locale settings of the operating system to English