Class-based activities and orchestrators are not recognized in .NET 8

Description

When upgrading to .NET 8, class-based activities and orchestrators (using Microsoft.DurableTask.Generators) are not recognized anymore by the runtime.

Expected behavior

Activities and orchestrators should become visible in list of functions when function app is running.

Actual behavior

Activities and orchestrators are not recognized and trying to start an orchestration does not result in an error, but nothing happens.

Relevant source code snippets

After creating a new .NET 8 function app in Visual Studio, add <PackageReference Include="Microsoft.DurableTask.Generators" Version="1.0.0-preview.1" /> to csproj and convert the sample code to:

using Microsoft.Azure.Functions.Worker;
using Microsoft.Azure.Functions.Worker.Http;
using Microsoft.DurableTask;
using Microsoft.DurableTask.Client;

namespace Fun;

public static class Function1
{
    [Function("Function1_HttpStart")]
    public static async Task<HttpResponseData> HttpStart(
        [HttpTrigger(AuthorizationLevel.Anonymous, "get", "post")] HttpRequestData req,
        [DurableClient] DurableTaskClient client)
    {
        // this is a generated method which indicates that the generator works
        var instanceId = await client.ScheduleNewWorkflowInstanceAsync("");

        return client.CreateCheckStatusResponse(req, instanceId);
    }
}

[DurableTask(nameof(SayHelloActivity))]
public class SayHelloActivity : TaskActivity<string, string>
{
    public override async Task<string> RunAsync(TaskActivityContext context, string input)
    {
        return input;
    }
}

[DurableTask(nameof(Workflow))]
public class Workflow : TaskOrchestrator<string, string[]>
{
    public override async Task<string[]> RunAsync(TaskOrchestrationContext context, string input)
    {
        var outputs = new List<string>
        {
            // also generated methods
            await context.CallSayHelloActivityAsync("Tokyo"),
            await context.CallSayHelloActivityAsync("Seattle"),
            await context.CallSayHelloActivityAsync("London")
        };

        return [.. outputs];
    }
}

Known workarounds

Use Function-based variants but that defeats the purpose.

App Details

runtime

Core Tools Version:       4.0.5455 Commit hash: N/A  (64-bit)
Function Runtime Version: 4.27.5.21554

packages

<PackageReference Include="Microsoft.Azure.Functions.Worker" Version="1.20.0" />
<PackageReference Include="Microsoft.Azure.Functions.Worker.Extensions.DurableTask" Version="1.1.0" />
<PackageReference Include="Microsoft.Azure.Functions.Worker.Extensions.Http" Version="3.1.0" />
<PackageReference Include="Microsoft.Azure.Functions.Worker.Sdk" Version="1.16.4" />
<PackageReference Include="Microsoft.ApplicationInsights.WorkerService" Version="2.22.0" />
<PackageReference Include="Microsoft.Azure.Functions.Worker.ApplicationInsights" Version="1.1.0" />
<PackageReference Include="Microsoft.DurableTask.Generators" Version="1.0.0-preview.1" />

Azure / azure-functions-durable-extension