After upgrading Spotlight to v15, all metrics show permanently as green, and no alarms are raised as before.
Alarm Action which diverts critical alarms to mobile devices may cause this, since the Cloud features have been disabled in v15.
Please check if there is an enabled Alarm Action that is suppressing, or diverting alarms. If there is an Alarm Action created to push critical errors to mobile devices, due to the Cloud feature of Spotlight being discontinued from v15, that rule may "hang" in some way, and the errors don't flow correctly. Once that is disabled, the alarms and metrics show correctly in Spotlight.
Also, if there is a Planned Outage setting enabled, this may suppress alarms also
