Copy markers left of first changed index

src/model/series.ts

@@ -576,14 +576,16 @@ export class Series<T extends SeriesType = SeriesType> extends PriceDataSource i
 			return;
 		}
 
-		const indexedMarkers = [];
-		const firstDataIndex = ensureNotNull(this._data.firstIndex());
 		let startIndex = this._indexedMarkers.findIndex((m: InternalSeriesMarker<TimePointIndex>) => m.time >= firstChangedPointIndex);
 
 		if (startIndex === -1) {
 			startIndex = 0;
 		}
 
+		// We can copy marks with a time point index < firstChangedPointIndex because we know they have not changed.
+		const indexedMarkers = this._indexedMarkers.slice(0, startIndex);
+		const firstDataIndex = ensureNotNull(this._data.firstIndex());
+
 		for (let index = startIndex; index < this._markers.length; index++) {
 			const marker = this._markers[index];
 			// the first find index on the time scale (across all series)

tests/e2e/graphics/test-cases/series-markers/set-series-data.js

@@ -0,0 +1,27 @@
+function runTestCase(container) {
+	const chart = LightweightCharts.createChart(container);
+
+	const candlestickSeries = chart.addCandlestickSeries();
+
+	candlestickSeries.setData([
+		{ time: '2021-10-01', open: 100, high: 110, low: 100, close: 110 },
+		{ time: '2021-10-02', open: 110, high: 110, low: 100, close: 100 },
+		{ time: '2021-10-03', open: 100, high: 110, low: 100, close: 110 },
+		{ time: '2021-10-04', open: 120, high: 130, low: 120, close: 125 },
+	]);
+
+	candlestickSeries.setMarkers([
+		{ time: '2021-10-01', position: 'aboveBar', shape: 'circle' },
+		{ time: '2021-10-02', position: 'aboveBar', shape: 'circle' },
+		{ time: '2021-10-03', position: 'aboveBar', shape: 'circle' },
+		{ time: '2021-10-04', position: 'aboveBar', shape: 'circle' },
+	]);
+
+	candlestickSeries.setData([
+		{ time: '2021-10-01', open: 100, high: 110, low: 100, close: 110 },
+		{ time: '2021-10-02', open: 110, high: 110, low: 100, close: 100 },
+		{ time: '2021-10-04', open: 120, high: 130, low: 120, close: 125 },
+	]);
+
+	chart.timeScale().fitContent();
+}