I struggled and not alone from reading the forums and support threads with the tap event on SfListView suddenly no longer working after some syncfusion or Forms update. I finally have a fix that worked for me. My Android project did not have Syncfusion.Xamarin.SfListView referenced. This worked with older Xamarin.Forms. After some version update this stops working. Referencing Syncfusion.Xamarin.SfListView in the android project fixes the issue.
I hope this helps someone