If you had an IP address licensing issue, I think you'd know real quick as you wouldn't be able to push a new policy to the firewall and many features would not work correctly. I doubt that is inhibiting your signature updates, much more likely to be the SHA-1/SHA-256 issue.
In the SmartView Tracker filter try filtering for log entries with a Type of "Control" (grey wrench icon), you should be able to find the exact error message about the update failing which should help.
--
My Book "Max Power: Check Point Firewall Performance Optimization"
Second Edition Coming Very Soon
Gateway Performance Optimization R81.20 Course
now available at maxpowerfirewalls.com