Sinon: "attempted to wrap createMessage which is already wrapped"

First, I've gone through all of the other posts related to this topic and implemented Sinon.sandbox(). Unfortunately, I am still getting the following error:

TypeError: Attempted to wrap createMessage which is already wrapped

Note that I'm using Ava for testing and in this case, I've set it to run in serial mode rather than parallel.

// Load modules

import Queue from '../lib/queue';

import test from 'ava';
import Sinon from 'sinon';
import Proxyquire from 'proxyquire';

// Globals

const FAKE_APPOINTMENT_ID = 'ab9e9495-fdbf-4607-8f57-01c6e91bd8f5';

let push;
let queueStub;
let sandbox;


// Test setup

test.beforeEach(() => {

    // create the sinon sandbox
    sandbox = Sinon.sandbox.create();

    // stub the queue module
    queueStub = sandbox.stub(Queue.prototype);

    // inject the stub
    push = Proxyquire('../lib/push', {
        './queue': queueStub
    });
});


test.afterEach(t => {

    sandbox.restore();
});

// Tests

test.only('sends an appointment approved push notification', async t => {

    await push.appointmentApproved(FAKE_APPOINTMENT_ID);

    t.true(queueStub.createMessage.calledOnce);
});


test.only('sends an appointment cancelled push notification', async t => {

    await push.appointmentCancelled(FAKE_APPOINTMENT_ID);

    t.true(queueStub.createMessage.calledOnce);
});


test.only('sends an appointment updated push notification', async t => {

    await push.appointmentUpdated(FAKE_APPOINTMENT_ID);

    t.true(queueStub.createMessage.calledOnce);
});

I've also tried switching beforeEach to before, and while the first of the 3 tests passes, the last two complete because the stub's call count never seems to reset. Maybe I'm misunderstanding the purpose of restore()

Thanks!

from Sinon: "attempted to wrap createMessage which is already wrapped"