Thank you for providing us the sample steps.
Can you be more specific about the RadComboBox configuration that you used to reproduce this behavior. Did you managed to observe it with our online demo?
Can you explain your implementation in more details and provide us some sample markup?
We need these details because we want to configure the control in the same way as your combo and to repeat these steps in order to investigate the issue.
All the best,
the Telerik team
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