Question:

After updating my device to the Android 10 (Q) OS, why does Smart Lock not activate when connected to a trusted device, and instead asks for a PIN, pattern, or password?

Answer:

This is because, in accordance with the latest security guidelines from the Android CDD (Compatibility Definition Document) policy on Android 10 OS, you now need to unlock your device using your PIN, pattern, or password only once per session. Afterwards, Smart Lock will function normally. When you turn on your screen after unlocking your phone, a circle around the Lock Unlocked symbol indicates that your phone remains unlocked until it's restarted or after four hours of inactivity.