Hyper-V hosts freezing during Rapid Recovery Agentless backup of VM's

We have been running Rapid Recovery 6..1.2 for over a year using Agentless Backup on our Hyper-V hosts to backup VM's without problems. We recently bought 3 new hosts to replace the current hosts which are end of life. All hosts (old and new) are running Windows Server 2012 R2 Datacenter and all are up to date with patching. However the new hosts become unresponsive, as do the VM's on them, for 2 mins every hour when the Agent process starts running on the host. We've tried upgrading both Core and Agent to 6.2 but this has made no difference. The older hosts, which are running the same version of Agent don't display this issue. If I install the agent on the VM's instead of using agentless backup on the new hosts, there's no problem.

The agentless backups do take place, that's not the problem, however Production servers and hosts which are basically unusable for 2 mins every hour is completely unacceptable and has a major impact on the business.

Has anyone else experienced these or similar issues?