Thank you for following along with our course and for your question.
See this post in another forum thread here: Challenge: Encoding JSON Arrays | raywenderlich.com - #3 by khuffie
The TL;DR is: It’s a known bug in previous Xcode releases, there is a workaround in that blog post, but Xcode 11.5 should fix that issue. This version came out last week so, if you haven’t already, update and give things a try 
Otherwise let me know as it might still be a bug in Xcode 11.5 when it should have been fixed there.
Thanks again 
