Some-symbols-of-a-WealthData-DataSet-are-never-executed-if-a-Date-Range-is-specified

CODE:
using System;
using System.Collections.Generic;
using System.Text;

using WealthLab.Core;
using WealthLab.Backtest;


namespace WealthScript3 
{
    public class MyStrategy : UserStrategyBase
    {
      static SortedSet<string> execSymbols = new();
      static SortedSet<string> btSymbols = new();
      
        public override void BacktestBegin()
        {
         info($"{Backtester.Symbols.Count} symbols in Backtester.Symbols, DataSet={Backtester.ExecutionDataSetName}");
         foreach(var bh in Backtester.Symbols) btSymbols.Add(bh.Symbol);
        }

        public override void Execute(BarHistory bars, int idx)
        {
         execSymbols.Add(bars.Symbol);
      }

        public override void BacktestComplete()
        {
         info($"{execSymbols.Count} symbols in Execute()");

         int numNever = btSymbols.Count - execSymbols.Count;
         info($"-- {numNever} Symbols never executed --");
         StringBuilder sb = new();
         btSymbols.ExceptWith(execSymbols);
         foreach(string sym in btSymbols) 
         {
            sb.Append(sym);
            sb.Append(", ");
         }
         info(sb.ToString());
        }

      private void info(string text)
      {
         WLHost.Instance.AddLogItem("ExecTest", text, WLColor.Blue);
      }
    }
}