Great!! Yes, structured logging does depend on newer OS features and does therefore require iOS 17.0+ to function with structured logging. That also includes simulators so you will need to be on newer simulators. Thanks!

It looks like there may be an environment variable set in your scheme. Can you check if something is there? Specifically OS_ACTIVITY_DT_MODE=1 or some other value? This will request Xcode use the old logging system and redirect os_log to stderr like this.