Spawning Hidden Belts

In Null Sec we have had our industry index over 4 at downtime for several days. We have been expecting larger than a medium belt to spawn but have not gone higher. Is it due to not yet having a level 4 in the I hub or does something else determine when large or greater belts arrive?

The industry ihub upgrades may not be installed or turned on iirc. Have the holding Corp check them and get that in place.

So it is all about the upgrades then? Nothing else is already in Null Sec?

increasing the industry index increases the adm. So your system will be harder to entosis (it will take more time).