I have inspected the provided code and noticed that some controls on the page were Ajax-enabled by both RadAjaxManager and RadAjaxPanel. Please note that you should not Ajax-enable controls multiple times as this may cause them to work incorrectly. Moreover, there are duplicate settings in the RadAjaxManager.
Try to remove the RadAjaxPanel from the page and also replace the duplicate settings from the RadAjaxManager and the controls should work as expected.
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