In version 1.5 what is the significance of the dark orange bars above and below "the line"?
When you look at it on M1 timeframe, it displays the tick volume of the given candle divided by 2. Positive for bullish candles, negative for bearish, and 0 for neutral. It decides bullish/bearish/neutral based on previous close to current close comparison.
The candle you are referring to is probably showing zero dark orange volume because its close is equal to the previous candle's close.