We have analyzed the query and the attached image and would like to let you know that the reported issue occurs only when we are not including the Init method of SfChipRenderer in the AppDelegate file of your Xamarin.Forms iOS project as per in below code snippet.
public override bool FinishedLaunching(UIApplication app, NSDictionary options)
return base.FinishedLaunching(app, options);
For more information, please refer the below UG link.
We have checked the reported issue with Material design also for both SfChip and SfChipGroup. Close button works fine at our end.
Please check this and let us know whether the reported issue has resolved or not. Still, you are facing the issue, please revert us the attached sample to reproduce the issue or provide more information to check further and provided a possible solution at the earliest.