vagrant up through the CDK server tooling failed because of an rsync problem. The tooling lost track of the state of the vagrant box. The vagrant box couldn't be stopped from inside of Eclipse.
The vagrant up failed because of an error with rsync. Something was confused about the user's home directory. It was trying to write to /home/username/.ssh, however, $HOME isn't /home/username, it's /cygdrive/c/Users/username, so /home/username/ doesn't exist.
The CDK server was shown as 'Started, Sychronized'.
The error message appeared in the server console tab. However the stop button wouldn't work. Provisioning had never finished so the OpenShift connection wasn't working either.
Synchronized seems misleading here, since no files had been sync'd yet.