Backtesting multi-symbol cBot gives inconsistent results depending on base chart (in 3.7)

I'm in the process of converting a cBot to be multi-symbol, but I get inconsistent results when backtesting on different charts.  Below is a minimal sample that shows the issue.  It is a very simple bot that sells when RSI for a symbol crosses above 70.  The bot runs on two uncorrelated symbols, EURUSD and CHFJPY.  If I run the bot with the same backtesting settings, over the same period (say over December 2019), the results are different depending on if I ran it on a 1h EURUSD chart instance, or on a 1h CHFJPY chart instance.  I'd expect to get the exact same trades regardless of which base chart the bot was attached to.  Here is the minimal sample code:

using System;
using System.Linq;
using System.Collections.Generic;

using cAlgo.API;
using cAlgo.API.Indicators;
using cAlgo.API.Internals;
using cAlgo.Indicators;

namespace cAlgo.Robots
{
    [Robot(TimeZone = TimeZones.UTC, AccessRights = AccessRights.None)]
    public class Test : Robot
    {
        // Multi symbol bot test
        string[] symbols = { "EURUSD", "CHFJPY" };
        
        List< RSI_Strategy > strategies = new List< RSI_Strategy >();
        
        protected override void OnStart()
        {
            foreach ( var sym in symbols )
            {
                var rsiStrategy = new RSI_Strategy();
                rsiStrategy.init( this, sym );
                strategies.Add( rsiStrategy );
            }
        }
    }
    
    
    // Sell when RSI crosses above 70
    public class RSI_Strategy 
    {
        RelativeStrengthIndex rsi;
        Robot bot;
        string symbol;
        
        public void init( Robot bot, string symbol )
        {
            this.symbol = symbol;
            this.bot = bot;
            
            Bars bars = bot.MarketData.GetBars( bot.TimeFrame, symbol );
            rsi = bot.Indicators.RelativeStrengthIndex( bars.ClosePrices, 14 );
            
            bars.BarOpened += OnBarOpened;
        }
        
        void OnBarOpened(BarOpenedEventArgs obj)
        {
            if ( rsi.Result.Last(1) > 70 && rsi.Result.Last(2) <= 70 )
            {
                bot.ExecuteMarketOrder( TradeType.Sell, symbol, 10000, symbol, 10.0, 10.0 );
            }
        }
    }
}