Thank you for the details, I built a test with that Picker implemented in a DataTemplate used by the TemplateSelector.
However, I was not able to replicate what you've reported on any of the platforms (Android, iOS or UWP). Please try the attached project and see this on your end. Disregard the project name's relevance, you'll find the RadListView and related classes on MainPage and MainPage.xaml.cs.
Note that the project uses Telerik UI for Xamarin 2019.2.603 and Xf 3.6 (the latest supported options).
In general, if a TemplateSelector is being invoked, then there was usually a property changed event, trigger or other update mechanism in play. If you could update my demo so that it replicates the issue and send it back to me, I can forward it to the development team for further investigation.
Since you cannot open a support ticket to attach a ZIP file, you can instead host it on DropBox/OneDrive/etc and send me a download link instead.
Before updating the demo, please try your implementation with a normal Xamarin.Forms ListView to eliminate if the problem is a Xamarin.Forms-specific issue or a Telerik RadListview-specific issue.
Lance | Technical Support Engineer, Principal
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