Same issue! Moreover, device activity monitor isn't even being instantiated in the app based on OS logs. Would be grateful for an update here if anyone has one. Thanks :)

Fully seconding this, Frederik! I found this thread because I’m facing an issue with DeviceActivity thresholds not firing at all. I’m also trying to understand how this behaves in production for apps that rely on usage-threshold relocking. Have you found any mitigation or ‘least broken’ implementation pattern that improves reliability, even if there’s no true workaround? Any OS-version-specific observations would be really helpful. Thanks in advance!

Hi, any updates on this? Facing the same issue, unfortunately. Shields are never applied. Filtering for deviceactivityd logs on the device continues to return 0 messages in the console app.