AWS .NET Serverless/SAM: Can I use AuthorizeAttribute on a Lambda function?

Question

I am trying to incorporate .NET's AuthorizeAttribute in my AWS Serverless Application Model project. In my startup.cs class, which is decorated with [LambdaStartup], in ConfigureServices(), I have the following:

services.AddAuthorization(authorization =>
{
    authorization.AddPolicy("HasDocReadPrivilege", policy =>
    {
        policy.RequireClaim("privileges", Constants.DocsReadPermission);
    });
});

And in Configure() I have app.UseAuthorization();

In my Functions.cs I have added the Authorize attribute to the function I wish to enforce authorization on, as follows:

[Logging(LogEvent = true, CorrelationIdPath = CorrelationIdPaths.ApiGatewayRest)]
[Metrics(CaptureColdStart = true)]
[Tracing(CaptureMode = TracingCaptureMode.ResponseAndError)]
[Authorize("HasDocReadPrivilege")]
public async Task<APIGatewayProxyResponse> MyFunction(
    APIGatewayProxyRequest request, 
    ILambdaContext context)
{
    //Do something
}

But it doesn't work. Even if I set Constants.DocsReadPermission to a value that is not included in the user's claims (parsed from the authorization header which contains a JWT bearer token), it still allows the user to call the function.

What am I doing wrong? Or is it simply that AWS Lambda functions don't recognize the Authorize attribute?