Unable to Deserialize Json in WebApi with JsonSubTypes in .NET 5, although able to in Console App

Question

I am trying to implement polymorphic deserialization in my project's web api. I have the following base and derived class.

Base class

    [JsonConverter(typeof(JsonSubtypes), "PointType")]
    public abstract class BasePointRule
    {
       public abstract string PointType { get; }
    }

Derived Class

    public class DayOfWeekPointRule : BasePointRule
{
    public int Id { get; set; }
    public decimal Mon { get; set; } = 0;
    public decimal Tue { get; set; } = 0;
    public decimal Wed { get; set; } = 0;
    public decimal Thu { get; set; } = 0;
    public decimal Fri { get; set; } = 0;
    public decimal Sat { get; set; } = 0;
    public decimal Sun { get; set; } = 0;
    public int GroupId { get; set; }
    public Group Group { get; set; }
    public override string PointType { get;} = "DayOfWeekPointRule";


    public DayOfWeekPointRule()
    {
    }
}

I get an error when posting the json for the child type to my Web Api controller. Here is the json with double quotes escaped:

{
    "PointType":"DayOfWeekPointRule",
    "Mon":0,
    "Tue":0,
    "Wed":0,
    "Thu":0,
    "Fri":0,
    "Sat":0,
    "Sun":0
}

Here is the web api controller method:

        [HttpPost("AddPointRule")]
    public IActionResult AddPointRule(BasePointRule rule)
    {

        ConfigurationService.AddPointRule(rule);
        return Ok();
    }

The error message I get is:

System.InvalidOperationException: Could not create an instance of type 'RosterCharm.Models.Rules.BasePointRule'. Model bound complex types must not be abstract or value types and must have a parameterless constructor. Record types must have a single primary constructor. Alternatively, give the 'rule' parameter a non-null default value. at Microsoft.AspNetCore.Mvc.ModelBinding.Binders.ComplexObjectModelBinder.CreateModel(ModelBindingContext bindingContext) at Microsoft.AspNetCore.Mvc.ModelBinding.Binders.ComplexObjectModelBinder.BindModelCoreAsync(ModelBindingContext bindingContext, Int32 propertyData) at Microsoft.AspNetCore.Mvc.ModelBinding.ParameterBinder.BindModelAsync(ActionContext actionContext, IModelBinder modelBinder, IValueProvider valueProvider, ParameterDescriptor parameter, ModelMetadata metadata, Object value, Object container) at Microsoft.AspNetCore.Mvc.Controllers.ControllerBinderDelegateProvider.<>c__DisplayClass0_0.<g__Bind|0>d.MoveNext() --- End of stack trace from previous location ---

If I change the parameter in the controller route from the base class to the derived class, the json is deserialized correctly.

If I implement the above in a console application and call the following then the json is deserialized to the derived type without issue as well:

var derivedType = JsonConvert.DeserializeObject<BasePointRule>(json);

This led me to think that the issue is specific to .Net (I am using .Net 5), and have tried ensuring I am using Json.NET (Newtonsoft.Json, I think) instead of System.Text.Json by calling the following in my startup.cs

services.AddControllers().AddNewtonsoftJson();

Any tips would be much appreciated. Am thinking to try implementing my own Json converter next but was hoping to be able to leverage the json subtypes library for ease.