Hi @Tom_Russell,
Our team has been looking into this and similar reports and what we’ve found is that this seems to be stemming from something on the Core or network that is blocking the Core’s connection to our servers. This might be firewall, antivirus, VPN, or even a VOIP system.
Do you have anything like this on your network? If you have a different machine that you can use temporarily as your Core does it exhibit the same issue when the current Core is in this state?