Continuing on from our conversation on DarkForce, here's a couple of screenshots attempting
to illustrate the problem.
In the first photo, I've deliberately entered an incorrect password for my SysOp account. Normally, that would be it. Express would kick you out *immediately*. However, as you can see from the BusyBBS screen, we're still connected and look at the time on SyncTerm - 1 minute and 32 seconds later and nothing has happened.

Now in this second screenshot, you can see where I attempted to login with SyncTerm on my Kubuntu Linux laptop. BusyBBS correctly told my laptop that it was "busy". However, on my
Mega ST4, it's still just sitting there, no logoff, no progression and on the Win10 box I originally attempted to login on, I'm sitting at the desktop.

The only solution is to stop and restart BusyBBS. That's not a problem when I'm home. I know about it and I can simply do that if I mistake logging in as SysOp. But...imagine if I was at the KY State Fair, or VCF Midwest...
I think I'd just use my other account...where it correctly disconnects after the 3rd wrong attempt :)