Can you see what process are running on ESX service console by using ps -ef | grep "anythingspecifichere" and use kill -9 PID command to kill it if you know something is running. I would use ps -ef | grep "machinename.vmx" to see anything running with that specific virtual machine being imported.
Usually restarting VC server services will clear all tasks but sometimes has to clear it from kill -9 PID command.
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Regards,
Stefan Nguyen
iGeek Systems Inc.
VMware, Citrix, Microsoft Consultant