Did you try that backup operation when the VM is added directly from the ESXi without the vCenter's act (so I mean you must have a direct connection from tivoli to the host not the vCenter server)?Please mark my comment as the Correct Answer if this solution resolved your problem
No we have not tried it. Are there any logs in vCenter or Tivoli I can see what is going on ?
I'm not sure about the Tivoli log file path, but for the VCSA please check the following log files:
Please mark my comment as the Correct Answer if this solution resolved your problem
You can back up virtual machines from a subclient or from a reinforcement set (to incorporate all subclients for the reinforcement set). For each subclient, you should add the virtual machines to be sponsored up in the subclient content.