We have recently configured new monitors which are part of a scheduled custom report however, they never shown up in the scheduled report.
The report was configured so that monitors with only tags set (Advanced -> Tags section of the Monitor configuration) would be considered. The newly configured monitor did not have those tags which is why it was not showing up in the report.
To include all Monitors by tag, you must select which tags you wish to include in the reports.
Tags are text labels that can be assigned to any monitor.
Enter any number of tags separated by spaces.