Steps to reproduce:
1. Create a new Xamarin.Forms project;
2. Add to it the NuGet package for SfCalendar for Xamarin.Forms;
3. Add to its respective iOS project the NuGet packages for SfCalendar for Xamarin.Forms and Xamarin.iOS;
4. Add a new page to the Xamarin.Forms project;
5. Add an SfCalendar to that page;
6. Run the application - it works;
7. Open the Xamarin.Forms Previewer;
8. Open the page.
The page is displayed in the Xamarin.Forms Previewer.
I apologise for adding the stack trace as an image. It's a problem of Xamarin.Forms Previewer - it allows neither for the entire text to be visible nor to copy it.
The same happens with other components, such as SfAutoComplete.