Thank you for posting your query on Microsoft Q&A, from above description I could understand that you have generated sample alert from Microsoft Defender for Cloud and are trying to List/GET those alerts via Graph API/Microsoft Security Center console but are not able to find any.
Please do correct me if this is not the case by responding in the comments section:
Alerts generated by Microsoft Defender for Cloud could only be fetched via Microsoft Rest API and not Graph API, Graph is Majorly used for M365, M365 Security, MEM and Entra ID services.
For Example to fetch sample alerts generated in Microsoft Defender For Cloud you need to use Alerts Rest API:
To list all alerts associated with the subscription you must use Alert-List:
The Output would look like the highlighted one below:
Which is a reference of Alert Shown in the UI:
The Alerts V2 Graph API references to This resource corresponds to the latest generation of alerts in the Microsoft Graph security API, representing potential security issues within a customer's tenant that Microsoft 365 Defender, or a security provider integrated with Microsoft 365 Defender, has identified.
Also as per Alerts and incidents Alerts from the following security providers are available via these rich alerts and incidents:
- Microsoft Entra ID Protection
- Microsoft 365 Defender
- Microsoft Defender for Cloud Apps
- Microsoft Defender for Endpoint
- Microsoft Defender for Identity
- Microsoft Defender for Office 365
- Microsoft Purview Data Loss Prevention Hence Alerts generated by Microsoft Defender for cloud could not be fetched.
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