I faced the same problem at customer site and unfortunately it was production VM.
It was migrated by DRS then stuck at 72 % and couldn't cancel the migration task also.
Here is my resolution
Resolution : This issue is only possible to fix via login to the specific host where the vm is residing which you can find out on the summary page of the VM.
Run these commands via SSH to restart the mgmt agent
- /etc/init.d/hostd restart
- /etc/init.d/vpxa restart
After restarting the Host will be lost connection and become responsive again and will connect to the vcenter.
After reconnecting the host in vCenter, the VM is fully operational.
Impact :There will be no impact on residing VM when you restart the management Agent on the host. Only current ongoing task like vMotion stops working and timeout error will popup.