Not all alerts are showing in OOTB view: "Alerts that are currently active"
Aria Operations 8.x
Preview Source is not properly selected.
To display all Active Alerts via the OOTB Views "Alerts that are currently active",
In Aria Operations 8.18
Operations > Views > Manage > (DEP) Alerts that are currently activeSelect Preview Source".Integrations > Container > Universe > UniverseAll active alerts will be displayed.
In Aria Operations 8.14
Visualize > Views > Manage > Alerts that are currently activeSelect Preview Source".All Objects > Container > Universe > Universe