I already answered to your question in your support ticket. However I will post the same answer here so others from the community can find it.
I can not be sure about your scenario and the reason behind this behavior. However, such behavior may occur if you use our NoXaml dlls. If you do, the controls used in your project will be created (added to the visual tree) but they will not be visualized because their visual representation (XAML code) is not available. You can read more information about the usage of our NoXaml dlls in this article
. If you are not using the NoXaml dlls we will kindly ask you to provide us with more information (and snippets) about your scenario. How you load your modules and how are they structured? If we reproduce that behavior on our side we will be able to suggest the best approach in your case.
I am looking forward to hearing from you.
Pavel R. Pavlov
the Telerik team