Nested RuleForEach: GetParentObjectAndPropertyName fails to find the PropertyInfo

[CreddenDCIU]

public class DemographicValidator : AbstractValidator<AppContext>
{
    public DemographicValidator() 
    {
        RuleForEach(x => x.Assignments).ChildRules(x =>
        {
            x.RuleForEach(x => x.StaffHistory).ChildRules(x =>
            {
                x.RuleFor(x => x.StartDate).NotEmpty().WithMessage("Start Date is required.");
            });
        }
    }
}

I've omitted most of the rest of the validation for brevity, as that all worked without issue until this one. Once it gets here it throws a null reference error when trying to get property.GetValue(model, null) because property is null.

private void GetParentObjectAndPropertyName(object model, string propertyPath, out object parentObject, out string propertyName)
{
	if (model == null)
	{
		throw new ArgumentNullException("model");
	}
	Queue<string> queue = new Queue<string>(propertyPath.Split('.'));
	Type type = model.GetType();
	while (queue.Count > 1)
	{
		string text = queue.Dequeue();
		string text2 = null;
		int num = text.IndexOf('[');
		if (num > 0)
		{
			text2 = text.Substring(num + 1, text.Length - num - 2);
			text = text.Remove(num);
		}
		PropertyInfo property = type.GetProperty(text);
		model = ((model == null) ? null : property.GetValue(model, null));
		if (text2 == null)
		{
			type = property.PropertyType;
			continue;
		}
		List<object> list = ((IEnumerable<object>)model).ToList();
		int index = int.Parse(text2);
		model = list[index];
	}
	parentObject = model;
	propertyName = queue.Dequeue();
}

It looks like it's trying to get AppContext.StaffHistory instead of Assignment.StaffHistory.