I have been having the same exact problem. I purchased the conbee II usb off of amazon in Sept of this year (2021).
The VM is running on my UNRAID server.
The workaround I have been using is to edit the VM config and uncheck the conbee II usb device, start the VM, stop the VM, edit the config and add the conbee II device back by clicking the check mark.
I did update the firmware of the conbee II hoping it would aleviate the problem but best I can tell it did not.
I am using the HASSOS qcow2 to boot the VM per these directions.
I am ready to migrate this off of the UNRAID server to another linux host and just run via zigbee2mqtt assuming getting off the VM will resolve the ‘no such device/file’ issue.