Update.
Based on detailed suggested steps by VSL Support the problem was fixed.
I'm not absolutely sure which of the steps did it, but I suspect it was entering specific inbound port permissions in my firewall settings. Instructions are found in the VE Pro manual under "Firewall"
W 10 i5-9600K 64 GB Synch - Woods, Brass, Perc I, Str Pro, Elt Str, Dua Str & Sordino, Prime Studio - Woods, Perc, Solo Str, Ch Str, Orch Str, App Str, Harps, Choir St Dim - Brass, Strings VE Pro, MIR Pro 3D, Vienna Suite Pro Cubase 14, St One 6, Dorico 5