Group server instance not restarting after shutoff

I’ve created a Group server with our Ubuntu 16.04 image on the Birmingham network. However, after I shut it off over the last week or so, I’ve not been able to start the instance back up. I also have the same issue with a user server, but my third server (which is also a user server) has restarted OK. A soft reboot could not be carried out on the server either.
Is there a know issue with restarting servers from the shutoff state? It’s not a major issue, as I can just terminate them and set up new ones with the image, but I wanted users thoughts on this.
Thanks in advance?