Discovery schedule is not working in the instance.
Quick discovery works, but when running the same discovery through the discovery schedule using the Discover Now button, discovery does not start. Not even the discovery status record is generated when discovery is running through the scheduler.
Customized Discovery script include.
Revert the Discovery script include to the out of box instance.
Navigate to: /nav_to.do?uri=sys_script_include.do?sys_id=a6cdaf5bc0a802550004f460b6c04967
Use out of box version for this script include. Verify issue is fixed with OOB script and review your customizations if needed to reapply.