The issue is observed when few active alarms remains stale on NSX manager. These alarms are seen only when queried using API but are not present in NSX GUI
3.2.3.52
To resolve these stale alarms execute below API using POST method
/api/v1/alarms/<alarm-id>?action=set_status
For Example,
POST /api/v1/alarms/XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX?action=set_status
The set_status can be OPEN, ACKNOWLEDGED, SUPPRESSED, or RESOLVED; If set_status is SUPPRESSED the suppress duration must also be specified
Refer NSXT API 3.2.1 for more information.