Your stop loss order can be triggered even when the trigger price doesn't appear to be hit on the charts due to limitations in how trading and charting platforms display price data.
How charting platforms display price data
Trading and charting platforms typically show only one tick (buy/sell transaction on the exchange) per second on a chart. However, multiple ticks can occur within that same second. This means your stop loss or limit order may have been executed during a tick that wasn't visible on the chart.
This limitation exists across all platforms, including NSE, Yahoo, NEST, and others.
How to verify your executed trades
You can verify all your executed trades directly on the exchange to confirm the exact execution prices and times. For detailed steps on checking your trades, see How to check all the trades placed with the broker on the exchange.