Xamarin: Binding ios protocol/delegate can't access enum defined in structs.cs

I'm currently in the process of creating ios bindings for the EDQueue library.

The Structs.cs file looks something like this:

using System;
using ObjCRuntime;

namespace EDQueue
{


    // => Enums attributed with[NativeAttribute] must have an underlying type of `long` or `ulong`
    [Native]
    public enum EDQueueResult : long
    {
        Success = 0,
        Fail,
        Critical
    }

}

The ApiDefinition.cs file is something like:

using System;
using Foundation;
using ObjCRuntime;

namespace EDQueue
{
    // typedef void (^EDQueueCompletionBlock)(EDQueueResult);
    delegate void EDQueueCompletionBlock(EDQueueResult result);

    // ETC....

    // @protocol EDQueueDelegate <NSObject>
    [Protocol, Model]
    [BaseType(typeof(NSObject))]
    interface EDQueueDelegate
    {
        // @optional -(EDQueueResult)queue:(EDQueue *)queue processJob:(NSDictionary *)job;
        [Export("queue:processJob:")]
        EDQueueResult Queue(EDQueue queue, NSDictionary job);

        //// @optional -(void)queue:(EDQueue *)queue processJob:(NSDictionary *)job completion:(EDQueueCompletionBlock)block;
        //[Export("queue:processJob:completion:")]
        //void Queue(EDQueue queue, NSDictionary job, EDQueueCompletionBlock completeBlock);

    }

    // ETC...
}

As written, the following error is produced: Error CS0426: The type name 'EDQueueResult' does not exist in the type 'EDQueue' (CS0426) (EDQueue) in file EDQueueDelegate.g.cs

That file looks like this when the error is thrown:

//
// Auto-generated from generator.cs, do not edit
//
// We keep references to objects, so warning 414 is expected

#pragma warning disable 414

using System;
using System.Drawing;
using System.Diagnostics;
using System.ComponentModel;
using System.Threading.Tasks;
using System.Runtime.InteropServices;
using System.Runtime.CompilerServices;
using UIKit;
using GLKit;
using Metal;
using MapKit;
using ModelIO;
using SceneKit;
using Security;
using AudioUnit;
using CoreVideo;
using CoreMedia;
using QuickLook;
using Foundation;
using CoreMotion;
using ObjCRuntime;
using AddressBook;
using CoreGraphics;
using CoreLocation;
using AVFoundation;
using NewsstandKit;
using CoreAnimation;
using CoreFoundation;

namespace EDQueue {
    [Protocol (Name = "EDQueueDelegate", WrapperType = typeof (EDQueueDelegateWrapper))]
    [ProtocolMember (IsRequired = false, IsProperty = false, IsStatic = false, Name = "Queue", Selector = "queue:processJob:", ReturnType = typeof (EDQueue.EDQueueResult), ParameterType = new Type [] { typeof (global::EDQueue.EDQueue), typeof (NSDictionary) }, ParameterByRef = new bool [] { false, false })]
    public interface IEDQueueDelegate : INativeObject, IDisposable
    {
    }
// ETC...
}

However, if I remove or comment out the [Protocol, Model] bit, the library builds without error.

I'm also getting a similar error if I uncomment the second function with the EDQueueCompletionBlock, which ultimately relies on the EDQueueResult enum.

The Structs.cs file's build action is set to ObjcBindingCoreSource.

Any help is truly appreciated. Thanks!