When CanvasJsAsCsv plugin is used with zoomEnabled, the controls in the page are scrambled. The “Save As Csv” link is appearing below the Reset button and scrambled. Not on the menu dropdown.
CanvasJSDataAsCSV plugin is not official plugin. However I observed that the plugin was updated recently and the issue you have mentioned seems to have been fixed. If the issue still persists kindly report it in their plugin page.
Also take a look at this JSFiddle for exporting chart data as CSV without any external plugin.