Please note that having Ajax on the page does not change the page life cycle. The same page events are still executed even on partial updates.
This said, would you try to disable Ajax in the application and see if the behavior changes? In case the issue persists, it is likely not Ajax related.
Also, would you try to use RadAjaxManager to Ajax-enable the controls as it is designed to be used in more complex scenarios. When using RadAjaxManager note that Ajax-ifying hidden controls is not supported. In such scenarios you should place the hidden control in a container that is always visible (e.g. Panel) and add that container to the AjaxSettings of RadAjaxManager.
If you prefer not to share your code publicly you could send a formal support ticket and attach your project there.
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