Hello @AndrewShaw
Thank you for reaching out on the community and telling us about your issue. I do apologize for the issue you're having. It sounds like it thinks you may not be connected to the Quicken server in general. In this case lets try signing out and back in to see if we're able to get some connectivity.
Thanks,
Quicken Francisco
https://www.quicken.com/support/advanced-data-file-troubleshooting-correct-problems-quicken-windows
Once you get the chance let us know what you're able to find out. From there we'll see what we able to find next.