While we do not release the IP before taking a snapshot we do stop the AppVolumes service before we shut down. I would definitely try stopping the service before you release the IP and see if that makes a difference.
I would do that suggestion indeed. Also check the svservice.log file on the agent VDI machine. You would also see it connecting there.
What we do saw before is that the agent took to long to merge the appstacks and when Windows logon was finished it was still attaching/merging appstacks and throw out a similar error.
If it is just this, you could hide the popup using this key
Off course this is just fooling the agent to not show the message. I would still suggest looking into the svservice.log
I had case in with support for this same issue. The problem appears to be fixed in 2.14.2.
Are you using any certificate for your AppVol manager ?
If not then "Disable certificate validation with App Volumes manager" while you installing agent on the VMs
I am using a certificate and I see nothing in the agent logs that make me believe it is a cert issue. Also, I am on the latest agent. I have proved it is not an image issue by unassigning all app stacks and the error goes away. I can duplicate this on demand by stopping and starting the App Volumes Service. As soon as I restart the service, the message pops up immediately. It's almost as if it is programmed to show this message when the service starts. I am using port 443 with enable cert validation and want to continue this. Curios if someone grabs just a normal vm in their environment and stops and starts the App Volumes Service on the desktop. Do you immediately get the pop up of "connection Error Unable to contact App Volumes Manager. Virtualization is disabled"? The message pops up before it could possibly go out and attempt to connect to the App Volumes Manager. It is instantaneous.