See the issue I posted a few weeks ago with solution from Apple ( https://developer.apple.com/forums/thread/696903 ). Your issue seems similar. The solution for my issue was to delete Swift Playgrounds and download/re-install it again. It worked.

Took awhile - but I just got feedback/resolution from Apple (I submitted this issue via Feedback Assistant). The solution was simple (I should have tried it on my own probably): Delete the Swift Playgrounds App and Re-install it. It worked!

Thanks for the suggestion. I just created a new Learn to Code 1 and unfortunately got exactly the same result (no go) and the same error message. I did submit feedback (same info as in this discussion thread) via the developer feedback app on my MacBook when I first noticed the problem.