i have an nearly identical problem as this guy: veeam-one-f28/heartbeat-is-missing-for-vm-t21181.html
We have a couple of Citrix Linked Clone VMs. Some of the Clones produced the "Hearbeat is missing" Error.
Everything in the VMs runs fine and in the vSphere Chart the Heartbeat seems ok.
I reinstalled vSphere Tools in the Citrix Master and recreated the clones, but the error comes up again. I thin about 2-3 Times a day.
Veeam One reports the following
Error Heartbeat Missing 06:10:55
Resolved Heartbeat Missing 06:14:18
During this Time vSphere show's me a constant heartbeat of 30
Any suggestion how we can resolve this issue?