Unable to display alert after modal popup

I have an issue I am unable to solve.

In this code:

var popupPage = new myPopup();

var taskCompletionSource = new TaskCompletionSource<bool>();

// Set up an event to resolve the task when the modal is dismissed
popupPage.Disappearing += (s, args) =>
{
    taskCompletionSource.TrySetResult(true);
};

// Push the modal and await its dismissal
await this.Navigation.PushModalAsync(popupPage);
await taskCompletionSource.Task;
await Task.Delay(100);

await MainThread.InvokeOnMainThreadAsync(async () =>
{
    await DisplayAlert("Update", "The file needs to be updated to the latest version. Do you wish to do this now?", "Yes", "No");
});

The popup is awaited properly and will not continue until I close the popup, however when it hits teh DisplayAlert(), the method just ends, there is no exeception thrown (I do have this enclosed in a try/catch) and there is no alert displayed.