Missing code after I reference dll in .NET project

I have .NET project that should reference dll(not a project reference) of class library.
The library has several classes and interfaces. I will explain only the ones that might be related to the problem.

Simple interface:

public interface IEmailMessageRepository : IGeneralRepository<EmailMessage>
{
    public Task<List<EmailMessage>> GetEmailsBySentStatus(bool sent);
}

Class that implements this interface:

public class EmailMessageRepository : GeneralRepository<EmailMessage>, IEmailMessageRepository
{
    public EmailMessageRepository(FishContext context) : base(context)
    {

    }
    public async Task<List<EmailMessage>> GetEmailsBySentStatus(bool sent)
    {
        return await _context.EmailMessages.Where(e => e.IsSent == sent).ToListAsync();
    }
}

and static class that extends IServiceCollection:

public static class ServiceCollectionsFish
{
    public static IServiceCollection RegisterFishServices(this IServiceCollection services, IConfiguration configuration)
    {
        services.AddDbContext<FishContext>(o =>
        {
            o.UseSqlServer(configuration.GetConnectionString("FishUA"));
            o.EnableDetailedErrors();
            o.EnableSensitiveDataLogging();
        });
        services.AddTransient<IEmailMessageRepository, EmailMessageRepository>();
        return services;
    }
}

Now, in another project that I want to reference this class library(dll), in the Program.cs I register my classes for DI:

        var host = Host.CreateDefaultBuilder()
            .ConfigureServices((context, services) =>
            {
                services.RegisterFishServices(config);
                services.AddTransient<IBasic, Basic>();
                services.AddTransient<IEmailMessageRepository, EmailMessageRepository>();
            }).Build();

Class that uses this repository:

private readonly IEmailMessageRepository _emailMessageRepository;

public Basic(IEmailMessageRepository emailMessageRepository)
{
    _emailMessageRepository = emailMessageRepository;
}

I can not build my project, because I get the following error:

“Error CS1061 ‘IEmailMessageRepository’ does not contain a definition for ‘GetEmailsBySentStatus’ and no accessible extension method ‘GetEmailsBySentStatus’ accepting a first argument of type ‘IEmailMessageRepository’ could be found (are you missing a using directive or an assembly reference?)”

When I open the ‘IEmailMessageRepository’, the body of the interface is empty.

Where may be the problem ?