Ontology New Experience: Data Agent and Graph Materialization Issues

Hello,

I am currently evaluating the Fabric Ontology new experience (Generation 2, Preview), and I have encountered the following three issues. I would like to confirm whether these behaviors are known limitations of the current Preview or unexpected issues.

Environment

• Microsoft Fabric capacity: F2
• Ontology: New experience (Generation 2, Preview)
• Data sources: Lakehouse and Eventhouse
  
  

1. Unable to add an Ontology to Fabric Data Agent
When I try to add an Ontology created with the new experience as a data source to a Fabric Data Agent, the operation fails with the following error:

• Error occurred while adding datasource. Failed to fetch schema for the data source.

To isolate the issue, I simplified the Ontology to contain only a single Shop entity and removed all Decimal properties and time-series bindings. With this minimal configuration, Graph materialization completes successfully.
However, adding the same Ontology to the Data Agent still fails with "Failed to fetch schema for the data source.
In the same environment, an Ontology created with the old experience (Generation 1) can be added to the Data Agent successfully. Therefore, the Data Agent issue does not appear to be caused by a Graph materialization failure.

2. Graph materialization fails when a Decimal property exists
When an entity contains a Decimal property, Graph materialization fails with HTTP 400. For example, my Shop entity contained the following property:

• Property: FloorAreaM2
• Type: Decimal

Graph materialization failed with the following error:

• FeatureNotImplemented: DECIMAL(P,S) graph properties are not enabled.

After removing the FloorAreaM2 property from the Ontology, Graph materialization completed successfully. I would like to confirm whether Decimal properties are currently unsupported for Graph materialization in the Ontology new experience.

3. Graph materialization fails when a time-series binding exists

Graph materialization also fails when I add a time-series binding to an entity. To isolate this issue, I reduced the time-series binding to only one property:

• Entity: Shop
• Source: TS_SalesHeader (Eventhouse)
• Property: SalesId
• Property type: Time series (Integer)
• Timestamp: SalesDateTime

Even with only this single Integer time-series property, Graph materialization fails with HTTP 400:

• ModelValidationError: [InvalidPropertyType] GraphType: Property type INVALID for property SalesId is invalid.

If I remove the time-series binding from the same Ontology, Graph materialization completes successfully. I also tested additional time-series properties, and the properties were reported as GraphType INVALID regardless of their underlying data types. Therefore, this does not appear to be an issue specific to Decimal properties.

Could you please clarify the following?

1. Is the Fabric Ontology new experience (Generation 2, Preview) currently supported as a data source for Fabric Data Agent?
2. Are Decimal properties currently supported when materializing an Ontology to Graph?
3. Are time-series bindings currently supported when materializing an Ontology to Graph?
4. If these scenarios are supported, are these known issues with the current Preview?
5. Are there any known workarounds or planned fixes?

Summary of test results

• Ontology Generation 1 -> Data Agent: Success
• Ontology new experience with only a single entity and static data binding, with no Decimal properties or time-series bindings -> Graph materialization: Success
• Same Ontology -> Data Agent: Failed ("Failed to fetch schema for the data source.")
• Ontology new experience with a Decimal property -> Graph materialization: Failed ("DECIMAL(P,S) graph properties are not enabled.")
• Ontology new experience with one Time series (Integer) property -> Graph materialization: Failed ("GraphType: Property type INVALID for property SalesId is invalid.")