I'd like to arrange for you to send me a diagnostic. Expect an email shortly.
BakerD and I determined that there were a couple deleted subnets that contributed to no scans taking place. I have added the specifics of the scenario within our defect tracking system.
We repaired the install with a sql statement (delete from ipam_scaninstance) and then a restart of the "IPAM Information Service". I believe this exact scenario to be fairly isolated.