How to turn off contact shadows in "USDZ" file for AR Quick Look?

Question

We are working with USDZ files and are having trouble with contact shadows especially with transparent objects.

Questions:

1) Is there a way to turn off contact shadows?

The AR Quick Look presentation in WWDC says there is a way to turn off contact shadows, but I'm unable to find any documentation on how.

2) Should contact shadows in the case of transparent objects be handles differently?

Here's a capture of a wineglass object:

Here you can download USDZ model .

Update 20/Nov/2018 : I have a bug report with Apple for this feature: https://bugreport.apple.com/web/?problemID=46180332

Update 22/Mar/2019 : Answered as well. Looks like this is now fixed in iOS 12.1.4.

Answer 1

Looks like this has been fixed in iOS 12.1.4.