Repeater with list of custom object

usually a repeater data source is a data table, have you tried converting your list of objects to a data table with the columns matching the field names?

No, because datas comes from external API and I wanted to bind it to repeater and use transformation to control how each item is displayed.

Download the universal api viewer with hierarchy support from the marketplace, in there you'll find how i do exactly what you are doing, converting a strongly typed api class to a repeater to transform. Already did that work for you and wrote the classes that take a list of .net objects and converts it into a proper transformable object. That's why i created that webpart.

http://devtrev.com/Resources/Universal-Api-Viewer

https://devnet.kentico.com/marketplace/utilities/universal-api-viewer-(with-hierarchy-support)

I think your transformation type is not set to Text/XML and because of that it doesn't not resolve macros :

If it is still does not work try convert it to DataTable. DataTable will work for sure.

public static DataTable ToDataTable<T>(List<T> items)
{
        DataTable dataTable = new DataTable(typeof(T).Name);

        //Get all the properties
        PropertyInfo[] Props = typeof(T).GetProperties(BindingFlags.Public | BindingFlags.Instance);
        foreach (PropertyInfo prop in Props)
        {
            //Defining type of data column gives proper data table 
            var type = (prop.PropertyType.IsGenericType && prop.PropertyType.GetGenericTypeDefinition() == typeof(Nullable<>) ? Nullable.GetUnderlyingType(prop.PropertyType) : prop.PropertyType);
            //Setting column names as Property names
            dataTable.Columns.Add(prop.Name, type);
        }
        foreach (T item in items)
        {
           var values = new object[Props.Length];
           for (int i = 0; i < Props.Length; i++)
           {
                //inserting property values to datatable rows
                values[i] = Props[i].GetValue(item, null);
           }
           dataTable.Rows.Add(values);
      }
      //put a breakpoint here and check datatable
      return dataTable;
}