Hi all, Seems like I was able to resolve the issue by switching off Siri & Search in Simulator Settings. Also I went through all of the installed apps and disabled everything there as well.

I have found the most-likely issue: Seems like when a command-line utility is run by an XPC (via NSTask API) then it needs entitlements to access Keychain API Command line utility and entitlements? Xcode ain't going to support this kind of behavoir! Except if to follow @eskimo1's instructions here: https:// developer.apple.com/forums/thread/129596 I am still waiting for another reply to my TSI #757702091 that will be definitive in terms of what should work and what cannot. Then I will update this post.

Hi @brennanAMZN thank you for your response! Unfortunately I did everything I found online, including checking out blog posts from 2009. What is actually happening is that due to stdout buffering, data is not being written to that stdout. What helped was to add fflush() calls right after the Swift.print() calls in the child process. I am writing down a series of blog posts related to this, however, what actually helped was a TSI response from an Apple Engineer.