Mapping DateTime Not Converting to the Correct Format

I have this mapper, and in the logic of mapping I will check if a property has an attibute CustomDateConverAttribute. If it has, I will call a function to Convert the string to the correct Format:

CreateMap<JToken, ModelOne>()

.ForAllMembers(opt =>
{
    opt.MapFrom(src => src.SelectToken(opt.DestinationMember.Name));
    opt.Condition((src, des, _, _, resolutionContext) =>
    {
        MemberInfo propDestination = opt.DestinationMember;
        string propName = propDestination.Name;

        //this is where we modify data with type mappers
        if (Attribute.IsDefined(propDestination, typeof(CustomDateConvertAttribute)))
        {
            opt.ConvertUsing(new CustomDateTimeConverter(), src => src.SelectToken(propName).ToString());
        }

        //map all
        return true;
    });
});

And this is what I'm calling:

public class CustomDateTimeConverter : IValueConverter<string, string>
{
    public string Convert(string source, ResolutionContext context)
    {
        DateTime dt;
        try
        {
            dt = DateTime.Parse(source);
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
            dt = DateTime.ParseExact(source, "dd/MM/yyyy h:mm:ss tt", CultureInfo.InvariantCulture);
        }

        return dt.Year + "-" + dt.Month + "-" + dt.Day + " " + dt.Hour + ":" + dt.Minute + ":" + dt.Second;
    }
}

However, it's not successfully being converted. How would I be able to convert the time format to the correct value?

UPDATE

To answer the question in the comments:
I basically have 2 APIs. One is all POST requests to a db. The posted data maps to a model of three properties:

public class BaseModel
{
    public int Id { get; set; }
    public string? DataReceived { get; set; }
    public int? Transfered { get; set; } = 0;
}

Then DataReceived accepts strings but majority of the data here is JSON.

The other API is for transferring the DataReceived to models in the second db. That's when I did the AutoMapper.

The CustomDateTimeConverter class implements the IValueConverter<string, string> interface. Since the source value is already a string, you don't need to specify the IValueConverter interface with string types. Instead, you can simply implement the IValueConverter<JToken, DateTime> interface directly.

public class CustomDateTimeConverter : IValueConverter<JToken, DateTime>
{
    public DateTime Convert(JToken source, ResolutionContext context)
    {
        string sourceValue = source.ToString();

        DateTime dt;
        if (!DateTime.TryParse(sourceValue, out dt))
        {
            dt = DateTime.ParseExact(sourceValue, "dd/MM/yyyy h:mm:ss tt", CultureInfo.InvariantCulture);
        }

        return dt;
    }
}

In the ForAllMembers configuration, you should use opt.MapFrom to specify the source member for mapping, instead of src.SelectToken(opt.DestinationMember.Name). src.SelectToken(opt.DestinationMember.Name) will always return null because opt.DestinationMember.Name refers to the destination member's name, not the source member's name.

CreateMap<JToken, ModelOne>()
    .ForAllMembers(opt =>
    {
        opt.MapFrom(src => src);
        opt.Condition((src, des, _, _, resolutionContext) =>
        {
            MemberInfo propDestination = opt.DestinationMember;
            string propName = propDestination.Name;

            if (Attribute.IsDefined(propDestination, typeof(CustomDateConvertAttribute)))
            {
                opt.ConvertUsing<CustomDateTimeConverter>();
            }

            return true;
        });
    });