"No service for type 'MediatR.IRequestHandler" on execution Azure Function

I'm using an Azure Function (v4) to upload data to a storage account. I use different project (Class libraries), that implement MediatR to execute commands. My code compilates fine but on runtime my function gives the following error:

I have a feeling it has something to do with either NuGet packages or Dependency Injection,but I cannot figure it out. I will add some of my code here to give a little bit of detail.

Azure Function Project

In my function.cs I call mediator

       public ImageLoaderFunction(IMediator mediator)       {           _mediator = mediator;       }        // In my Run() method        var result = await _mediator.Send(new UploadImageCommand(filestream, blobName));

Startup.cs
builder.Services.AddMediatR(cfg => cfg.RegisterServicesFromAssemblies(Assembly.GetExecutingAssembly()));

Class Library Project

UploadImageCommand.cs
public record UploadImageCommand(FileStream FileStream, string BlobName) : IRequest<bool>;

UploadImageHandler.cs

public class UploadImageHandler : IRequestHandler<UploadImageCommand, bool>{    private readonly IMyBlobService _myBlobService;    public UploadImageHandler(IMyBlobService myBlobService)    {        _myBlobService = myBlobService;    }    public async Task<bool> Handle(UploadImageCommand request, CancellationToken cancellationToken)    {        return await _myBlobService.UploadImageAsync(request.FileStream, request.BlobName);    }}

I have tried different approaches of adding MediatR to the services in Startup.cs, but without success.