Fixed #6566, zAxis wasn't updated through chart.update().

js/parts/Dynamics.js

@@ -291,7 +291,8 @@ extend(Chart.prototype, /** @lends Highcharts.Chart.prototype */ {
 		// update the first series in the chart. Setting two series without
 		// an id will update the first and the second respectively (#6019)
 		// chart.update and responsive.
-		each(['xAxis', 'yAxis', 'series', 'colorAxis', 'pane'], function (coll) {
+		each(['xAxis', 'yAxis', 'zAxis',
+			'series', 'colorAxis', 'pane'], function (coll) {
 			if (options[coll]) {
 				each(splat(options[coll]), function (newOptions, i) {
 					var item = (

samples/unit-tests/3d/zaxis-update/demo.details

@@ -0,0 +1,5 @@
+---
+ resources:
+   - https://code.jquery.com/qunit/qunit-2.0.1.js
+   - https://code.jquery.com/qunit/qunit-2.0.1.css
+...

samples/unit-tests/3d/zaxis-update/demo.html

@@ -0,0 +1,7 @@
+<script src="https://code.highcharts.com/highcharts.js"></script>
+<script src="https://code.highcharts.com/highcharts-3d.js"></script>
+
+<div id="qunit"></div>
+<div id="qunit-fixture"></div>
+
+<div id="container"></div>

samples/unit-tests/3d/zaxis-update/demo.js

@@ -0,0 +1,39 @@
+QUnit.test('zAxis update through chart.update() (#6566)', function (assert) {
+    var chart = Highcharts.chart('container', {
+        chart: {
+            type: 'scatter',
+            options3d: {
+                enabled: true
+            }
+        },
+        zAxis: {
+            min: 10,
+            max: 20
+        },
+        series: [{
+            data: [
+                [5, 5, 5],
+                [10, 10, 10],
+                [15, 15, 15],
+                [20, 20, 20],
+                [25, 25, 25]
+            ]
+        }]
+    });
+
+    chart.update({
+        zAxis: {
+            min: 0,
+            max: 30,
+            labels: {
+                enabled: false
+            }
+        }
+    });
+
+    assert.strictEqual(
+        chart.series[0].points[0].isInside && chart.series[0].points[4].isInside,
+        true,
+        'zAxis updated'
+    );
+});