There are times when an Unattended session gets "stuck" with GoTo Resolve. There is no way to kill those sessions, meaning you can't otherwise connect again to the machine. This can sometimes happen if you're already connected and the remote machine loses and then regains connectivity.
The session remains stuck for hours and you cannot reconnect.
Rebooting the remote PC does not help.
The only resolution I've found is to start an Instant Support session with a person on the other end, connect to that, uninstall the Unattended access application, reinstall it, re-verify the PC in the Console, and then connect to the newly-added machine. During your new connection, the old session remains stuck for hours and hours.
It feels like the "stuck" session is on the GoTo side, in their cloud. We should be able to kill those or report that they are no longer active.