I had the same issue. To fix it helps to understand how this diagram works:
Inside 'Application Map' the items will be connected by correlation of dependency entities (send by Client) with request entities (send by Server):
- dependencyTelemetry.OperationId = requestTelemetry.OperationId
- dependencyTelemetry.Id = requestTelemetry.ParentId
The common approach for http calls seems that client sends required info as part of http request header. On both ends either own code per service method or middleware services handling request/send pipeline will be required.
The use of nuget Microsoft.ApplicationInsights.AspNetCore related to .NET Core 3.1 will add such services.
Example of http header send by this nuget package, version 2.13.0 + using default configuration:
- Request-Context: appId=cid-v1:12345678-60ba-4f61-ae37-07da9dc13267
- Request-Id: |abcdefdc99366a48a3886f34fb41c781.0102cca5a4ecc64f.
- traceparent: 00-abcdefdc99366a48a3886f34fb41c781-0102cca5a4ecc64f-00
where
- Request-Context: appId as shown in AplicationInsights portal. legacy + for scenarios connecting 2 different Application insights
- Request-Id: Legacy but current used header to transfer operation id + parent
traceparent: Adds support for upcoming new W3C standard
abcdefdc99366a48a3886f34fb41c781: OperationId, 16-byte as hex by W3C standard
0102cca5a4ecc64f: ParentId, 8-byte as hex by W3C standard
see also document 'Telemetry correlation in Application Insights'
https://docs.microsoft.com/en-us/azure/azure-monitor/app/correlation