An update midweek (~10 Feb 21) changed the nature of the WARP client when using Windows 10 Firewall.
A new rule needs to be added to allow the warp-svc.exe INBOUND (not just out, as it used to be).
Being a bit thick, it took me some time to work this out. Thought a heads up might be helpful to others.
I use Malwarebytes Windows Firewall Control as the client to manage the Windows firewall and clamp down pretty hard on programs, services and ports in order to stop the incessant flood of data going back to MS.