Problem with moving average bias

Hi all, I am having a problem with an exponential moving average filter, where two 50-period EMA's, one applied to high prices and one to low prices, set the buy and sell direction.

For the most part, the filter works as intended. However, if the price is lower than the high EMA, buys cannot take place and vice versa (if the price is higher than the low EMA, no selling).

On backtesting, positions seem to still stay open even when going past the set limits.

using System;
using System.Linq;
using cAlgo.API;
using cAlgo.API.Indicators;
using cAlgo.API.Internals;
using cAlgo.Indicators;

namespace MA_Bias
{
    [Robot(TimeZone = TimeZones.UTC, AccessRights = AccessRights.FullAccess)]
    public class cAlgo : Robot
    {
        private double _volumeInUnits;

        [Parameter("Label", DefaultValue = "MA Bias")]
        public string Label { get; set; }

        [Parameter("Starting Volume (Lots)", DefaultValue = 1.0, MinValue = 0.01)]
        public double StartingVolumeInLots { get; set; }

        [Parameter(DefaultValue = 10, MinValue = 1)]
        public int StopLoss { get; set; }

        [Parameter(DefaultValue = 15, MinValue = 1)]
        public int TakeProfit { get; set; }

        //public static TimeFrame Minute15 { get; set; }

        private ExponentialMovingAverage _MA_50_Buy;
        private ExponentialMovingAverage _MA_50_Sell;
        private bool MA_BiasBuy;
        private bool MA_BiasSell;

        protected override void OnStart()
        {
            // Declare necessary vars
            _volumeInUnits = Symbol.QuantityToVolumeInUnits(StartingVolumeInLots);
            MA_BiasBuy = false;
            MA_BiasSell = false;
            _MA_50_Buy = Indicators.ExponentialMovingAverage(Bars.HighPrices, 50);
            _MA_50_Sell = Indicators.ExponentialMovingAverage(Bars.LowPrices, 50);
        }

        protected override void OnBar()
        {
            var ActiveBuy = Positions.Find(Label, SymbolName, TradeType.Buy);
            var ActiveSell = Positions.Find(Label, SymbolName, TradeType.Sell);

            // MA Bias
            if (Symbol.Ask > _MA_50_Buy.Result.LastValue)
            {
                MA_BiasBuy = true;
                MA_BiasSell = false;
            }

            else if (Symbol.Bid < _MA_50_Sell.Result.LastValue)
            {
                MA_BiasSell = true;
                MA_BiasBuy = false;
            }

            if (MA_BiasBuy == true)
            {
                if (ActiveSell != null)
                {
                    ClosePosition(ActiveSell);
                }
            }

            if (MA_BiasSell == true)
            {
                if (ActiveBuy != null)
                {
                    ClosePosition(ActiveBuy);
                }
            }

            //Open Buy
            if (MA_BiasBuy == true && ActiveBuy == null)
            {
                if (ActiveSell != null)
                {
                    ClosePosition(ActiveSell);
                }
                ExecuteMarketOrder(TradeType.Buy, SymbolName, _volumeInUnits, Label, StopLoss, TakeProfit);
            }

            //Open Sell
            if (MA_BiasSell == true && ActiveSell == null)
            {
                if (ActiveBuy != null)
                {
                    ClosePosition(ActiveBuy);
                }
                ExecuteMarketOrder(TradeType.Sell, SymbolName, _volumeInUnits, Label, StopLoss, TakeProfit);
            }
        }

    }
}