Top Windows errors report is a very useful report which shows the most common Windows errors in your organization.
In case you see gap in data or the report is empty, please check the following settings:
1. Go in the Real Time Console to Settings -> Events Pane Settings
2. Make sure the option "Collect Error Events" is checked
3. Go to Settings -> Triggers Settings
4. Make sure both Errors in Application log and Errors in System log triggers are enabled
5. To verify the data is collected, you can go to the Incidents Pane and verify that Windows Errors incidents are being collected successfully.
Without those settings enabled, the report will be empty.