ListBoxFor in .NET Core not binding

I cannot get this ListBox to have a value. It worked in MVC4.5, from which I am translating; cannot get to work in MVC Core. Swear it was working at some point; now it is not.

Have tried: https://stackoverflow.com/a/19144613/2496266 https://stackoverflow.com/a/40308906/2496266 etc.

View

        <div class="tb-field desc-field">
            @Html.ListBoxFor(model => model.workerRequests,
                new SelectList(ViewBag.workerRequests, "Value", "Text"),
                    new { id = "workerRequests2_WO-"+ Model.ID, tabindex = "22", style="min-width: 16em;"}
            )
        </div>

Controller (GET)

            wo.workerRequests = new List<ViewModel.WorkerRequest>();
            ViewData["workerRequests"] = new SelectList(wo.workerRequests);
            return PartialView("Create", wo);

Controller (POST)

        public async Task<ActionResult> Create(WorkOrder wo, string userName)
        {
            ModelState.ThrowIfInvalid();
            var modelUpdated = await _adaptor.TryUpdateModelAsync(this, wo);
            // ... "wo.WorkerRequests" is empty here ^
        }

Entity

        public virtual ICollection<WorkerRequest> workerRequests { get; set; }

Additional info:

Apparently it is coming across in the Request, but as a StringValue:

...apparently all of them are string values. It's not getting bound to its desired type.

Basically:

1. It has getters and setters on the entity.
2. I'm populating the ViewData before serving the page.
3. I'm using a SelectList(arg) where arg is of type myModel.myProperty.

We are selecting the Worker in the WorkerRequest from the database (nested type). Is this due to the lazy-loading bugs? What am I doing wrong?