Update:
By hunting around, I've figured out how to get it working.
- Update iLok License Manager to latest version.
- Manually start the PACE License Manager services.
- Launch S1v3.3.1 in Windows 8 compatibility mode with admin rights.
All of these are known worksteps to resolve other issues. Not sure if it matters, but only THIS order of activity got it moving for me. Hope that helps.