SYMPTOM:
Even though some alerts are detected, Operations Manager does not display any of them in the Alerts page as shown below.

CAUSE:
One possible cause for this issue is that the Health Center Repository folder "\Repository\RTAlerts" contains too many ".RTAlert_RTAlert" files, and the system may hang by trying to show or load all the files.
ACTION:
Manually move old .RTAlert_RTAlert files to the History folder.

Notes:
When alerts are deleted via Operations Manager, the deleted alerts will also be moved to this history folder.