Automapper - Map Complex object from Dictionary

Question

I'm trying to map this:

var values = new Dictionary<string, object>()
{
    ["Address.City"] = "New York",
    ["FirstName"] = "First Name",
    ["LastName"] = "Last Name"
};

into this:

public class Person
{
    public string FirstName { get; set; }
    public string LastName { get; set; }

    public Address Address { get; set; }
}

public class Address
{
    public string City { get; set; }
}

If I don't change any config, I get Address as null. I've tried different approaches. A resolver or just editing my dictionary in the MapperConfiguration like this:

var config = new MapperConfiguration(cfg => {
    const string addressPrefix = "Address.";

    cfg.CreateMap<IDictionary<string, object>, Person>()
    .ForMember(x => x.Address, x => x.MapFrom(c => new Dictionary<string, object>(c.Where(dic => dic.Key.StartsWith(addressPrefix)).ToDictionary(dic => dic.Key.Replace(addressPrefix, string.Empty), dic => dic.Value))));

    cfg.CreateMap<IDictionary<string, object>, Person>()
        .ForMember(dest => dest.Address, opt => opt.ResolveUsing<PersonResolver>());
});
var mapper = config.CreateMapper();
var person = mapper.Map<Person>(values);

Both cases I successfully get the Address mapped right, but I lose the First and Last Name. Is there a way to reset the mapper to default for other members?

My resolver:

public class PersonResolver : IValueResolver<IDictionary<string, object>, Person, Address>
{
    public Address Resolve(IDictionary<string, object> source, Person destination, Address destMember, ResolutionContext context)
    {
        const string addressPrefix = "Address.";
        var address = new Address();

        if (source.Keys.Any(x => x.StartsWith(addressPrefix, StringComparison.InvariantCulture)))
        {
            var addressItems = source
                .Where(dic => dic.Key.StartsWith(addressPrefix, StringComparison.InvariantCulture))
                .ToDictionary(dic => dic.Key.Replace(addressPrefix, string.Empty, StringComparison.InvariantCulture), dic => dic.Value);

            address = context.Mapper.Map<Address>(addressItems);
        }
        return address;
    }
}