Thank you for your feedback.
The reported behavior is caused by the fact that some of the RadBarcode controls set and validate the Text property in code. Binding to a property from your ViewModel has a lower precedence than setting it locally in code which means the binding is ignored. That's why in order the binding to work you need to set the Mode to TwoWay which has higher precedence than OneWay and setting a local value. You can take a look at the Dependency Property Setting Precedence List
article which could help you better understand the mentioned behavior.
Indeed this behavior is not described in our documentation. I have logged internal item to include this in the documentation of the RadBarCode control. Your Telerik Points have been updated for this report.
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