Azure will reset your VMs when you update their configuration. Normally this involves a rolling reset but as you only have one instance this was not possible.
Thanks for the info. I thought changing Scale would keep original server and just add new ones. But I guess it is a bit more intrusive.
Should be back up now. Mostly... If you get page not found, new DNS record didn't propogate yet. You can still use dotnetfiddle-prod.cloudapp.net or 191.234.40.