Thank you for contacting Telerik Support. This is not the default behavior of RadDatePicker, I have recorded a short video trying to reproduce the problem by following the scenario from your screencast. In both cases the control was working fine, I've actually included several controls that require viewstate and do postback and they have all preserved their values as expected. Can you please let me know if the issue reproduces on a blank project created with the same version of the project manager. Thanks in advance.
All the best,
the Telerik team
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