Sending OpenTelemetry traces from net8 to Seq don't seem to work (for me)

[jbennink]

Describe the bug
Once I set things up -- I think correctly -- I could net get traces to show in Seq.
I made a small repro in github OpenTelemetryTestingDefaultIlogger based on the WeatherForecast WebApi template adding as little as possible to get it to work with OpenTelemetry.

P.S. This might not be a bug, but more some seup issue on my part but I scoured the web and could not find any better documentation of samples without them either being non complete or very hard to digest.

To Reproduce
Steps to reproduce the behavior:

1. First setup a local Seq container (see included docker-compose)
2. Then run the project as-is
3. Use the (included OpenTelemetryTestingDefaultIlogger.http) to execute an api call
4. Check Seq to see the "Calling Weatherforcast" log entry, check the Trace dropdown and choose Show (see the screenshot)
5. It says "The trace does not contain any spans". But as far as I could figure out I did using an ActivitySource "WeatherApi" that was added in program.cs which created an Activity (and an inner activity). The ConsoleExporter does show both in the Console.

Expected behavior
I would have expected to see a trace like I have seens in some screenshots but I could never find actual complete samples code of the thing

Not to add 2 issues into one but I could also not get logging to work with otlp, on;y the builder.AddSeq() method seemed to get any logs to Seq.

Screenshots

Environment (please complete the following information):

• OS: Windows 11
• Browser Edge
• Seq Version 2024.3.12250
• Using Docker? Yes