Thank you for sending the detailed description of the case.
The described behavior of RadComboBox and the Text property is an expected one. We are using the Text property internally in our code when the ComboBox is Editable - the Text is of great importance for the selection of the item. Basically, if the Text property of the control gets changed after a selection is made the selection will be cleared - that will affect some of the other functionalities of the control. Because of that we do not recommend changing the Text of the control after a selection is performed.
Could you please provide us some more information about your scenario - why exactly do you need to change the Text of ComboBox after a selection? Are you using some of the other functionalities of the control - a code-snippet with the Xaml of RadComboBox will also be helpful so, we could thing of an approach that will suit your requirements?
We are looking forward to hearing from you.
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