App activity: If your app hasn't been used enough or hasn't encountered certain events (like crashes or high battery usage), MetricKit may not have enough data to send for the past 24 hours.

Background usage: MetricKit collects data while the app is running or in the background. If the app is not running or has limited background activity, it might not generate or report certain logs (e.g., battery or network).

Test on a real device and make sure the app runs continuously or in the background for a significant period. Allow it to process background events like crashes, network calls, or high CPU usage.