oData v4 filtering by DateTime, string not converting to DateTime

My URI:

$filter=IsActive eq true and IsAutomated eq true and WebSite ne null    and WebSite ne '' and LastUpdated le 2018-12-30T23:59:59.99Z

Controller:

private readonly BrokerForgeContext _ctx;[EnableQuery(PageSize = 20)][HttpGet]public IActionResult Get(){    return Ok(_ctx.Locations);}

Startup:

private static IEdmModel GetEdmModel(){    ODataConventionModelBuilder builder = new ODataConventionModelBuilder();    builder.EntitySet<CashBidPrice>("CashBidPrices");    builder.EntitySet<Location>("Locations");    builder.EntityType<CashBidPrice>().Collection.Function("DeleteToday").Returns<bool>();    return builder.GetEdmModel();}

Entity Model:

public partial class Location{    [Key]    public int LocationId { get; set; }    public int? Loc_Id { get; set; }    public string Name { get; set; }    **[[ REMOVED FOR BREVITY ]]**    public DateTime? LastUpdated { get; set; }}

I want to get all Locations where the LastUpdate record is less than today, but having some major issues with filtering on the LastUpdated record. Everything else works great.

The error:

An unhandled exception occurred while processing the request.SqlException: Conversion failed when converting date and/or time from character string.
System.Data.SqlClient.SqlConnection.OnError(SqlException exception, bool breakConnection, Action<Action> wrapCloseInAction)
TargetInvocationException: Exception has been thrown by the target of an invocation.
System.RuntimeMethodHandle.InvokeMethod(object target, object[] arguments, Signature sig, bool constructor, bool wrapExceptions)