Hi Jason,
Thank you for contacting Syncfusion support.
We have checked the Gorilla Player with SfListView control and it is not working as you reported. So, we have tried with the Custom controls(customized a Label in PCL and in corresponding renderer) in Gorilla Player and seems that it is not working with Xamarin Forms too. So, we have raised a support ticket regarding this to the Gorilla Player support team. And, we will let you know the further updates once they have resolved the reported issue.
You can keep track the status of this issue in the following link:
However, we have provided support for “SfListView in Xamarin Previewer(Designer)” by which you can achieve your requirement “Design the data templates with SfListView” using Xamarin Forms Previewer which enables you to see a live preview of your XAML page without having to run it on a simulator or device and the support will be included in our upcoming 2017 Volume 1 SP 2 release which is scheduled to be rolled by end of this month.
Please let us know if you require further assistance.
Regards,
Dinesh Babu Yadav