This happens usually when Spectrum cannot determine where to place the alarm and the alarm is placed on the Fault Isolation model.
I would recommend to make the change from the VNM model under Fault Isolation settings for the option "Unresolved Fault Alarm Disposition" from the default "Fault Isolation Model" to "Device in Fault Domain", that way Spectrum will pick the device with the highest criticality and will assign the alarm to that device.
https://docops.ca.com/ca-spectrum/10-1-to-10-1-2/en/managing-network/modeling-and-managing-your-it-infrastructure/fault-management/fault-isolation-settings
- Unresolved Fault Alarm Disposition
If information about the connectivity of your network model is incomplete, CA Spectrum may be unable to find the root cause of a network outage. In this case, the status of all devices affected by the outage is set to gray, and a red unresolved fault alarm is generated. This alarm indicates that CA Spectrum has lost contact with a group of devices, but was unable to pinpoint the cause.
All of the devices to which CA Spectrum has lost contact are listed in the impact scope of the alarm. The model name and other details of the lost devices also appear in the event that generated the alarm.
The Unresolved Fault Alarm Disposition field lets you control how the unresolved fault alarm is generated. When set to Fault Isolation Model, the alarm will be generated on the Fault Isolation model. When set to Device In Fault Domain, the alarm will be generated on one of the devices with which CA Spectrum has lost contact. When determining which device to generate the alarm on, CA Spectrum looks for the device with the highest criticality. If the highest criticality is shared by two or more devices, CA Spectrum generates the alarm on the first of these devices that it finds. If all devices have the same criticality, then CA Spectrum chooses the device with the lowest model handle.