I have tested previously attached sample page with version 2012.3.1308 and everything is working as expected in all browsers.
Since we are not able to replicate the issue locally, it is hard to determine the reasons behind this behavior on your end. Could you please test this in different browsers and see if the issue is still present or it is only observable in IE 9? Additionally, could you please debug and elaborate if the ExportToPdf command is firing. You could do this by setting break point in the ItemCommand server-side event handler:
sender, GridCommandEventArgs e)
Looking forward to your reply.
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