Darva's Box on Renko doing Weird Stuff

Question

Could anyone help me understand why sometimes this indicator fires a Buy/Sell alert without plotting Buy/Sell on the chart and other times plots a Buy/Sell on the chart without firing a Buy/Sell alert? This is specifically on Renko Traditional set to 0.0012 for forex instruments. Any input is appreciated.

//@version=5

indicator('Darvas Box Buy Sell', overlay=true)

boxp = input.int(defval=5, title='Length', minval=1, maxval=500)

LL = ta.lowest(low, boxp)
k1 = ta.highest(high, boxp)
k2 = ta.highest(high, boxp - 1)
k3 = ta.highest(high, boxp - 2)

NH = ta.valuewhen(high > k1[1], high, 0)
box1 = k3 < k2
TopBox = ta.valuewhen(ta.barssince(high > k1[1]) == boxp - 2 and box1, NH, 0)
BottomBox = ta.valuewhen(ta.barssince(high > k1[1]) == boxp - 2 and box1, LL, 0)

plot(TopBox, linewidth=2, color=color.new(#4CAF50, 0), title='TBbox')
plot(BottomBox, linewidth=2, color=color.new(#FF0000, 0), title='BBbox')

Buy = ta.crossover(close, TopBox)
Sell = ta.crossunder(close, BottomBox)

alertcondition(Buy, title='Buy Signal', message='Buy')
alertcondition(Sell, title='Sell Signal', message='Sell')

plotshape(Buy, style=shape.labelup, location=location.belowbar, color=color.new(#4CAF50, 0), size=size.tiny, title='Buy Signal', text='Buy', textcolor=color.new(color.black, 0))
plotshape(Sell, style=shape.labeldown, location=location.abovebar, color=color.new(#FF0000, 0), size=size.tiny, title='Sell Signal', text='Sell', textcolor=color.new(color.white, 0))

Answer 1

Because Renko bar prices are synthetic and they do not reflect market prices at any precise moment in time, as normal bars do,

Please read this, this and this.