I believe this problem started before 1503.
Starting a week or so ago the VE Pro Server connection window to Studio One began showing no available instances. Nothing to connect to, despite an open, running VEPs with multiple instances. It would crash Studio One when I clicked "Connect" just to see what would happen. This never happened to me until about a week ago.
Yesterday I uninstalled and reinstalled VE Pro, restarted my computer, and that solved things. At least I thought so, until my first attempt to connect this morning. No instances showing. I verified I am running 1503. VE Pro is unusable when this happens. If I can't connect to my instances, I can't use it.
Edited to add:
I just used Vienna Assistant to again uninstall / reinstall VE Pro. I noticed that Assistant now shows the latest version was 7.2.1495 but that 7.2.1503 was still what was still my installed version.
I am going to try uninstall / reinstall and restart again and see what happens.
Edited to add:
Same thing. 1503 installed, 1495 latest version. No connections available.
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