Starting with Android 7, Google changed the battery management such that active apps will stop running when the device goes to sleep.  Unlike iOS, Android does not offer an option for "Sleep = Never".  The max period offered is 30 minutes.

This means that when timing a race with RFID or NFC chips, someone would need to touch the screen every 30 minutes or so.  Not very practical.

Android offers a way to change this behavior for a specific app, but it's not easy to find:

1. Tap the "Settings" app on your Android device
2. Tap the "Battery" option
3. Tap the 3 vertical dots in the top right corner
4. Select "Battery optimization"
5. Tap the "Not optimized" dropdown and select "All apps"
6. Tap the Webscorer app icon
7. Select "Don't optimize" on the popup

This will keep the Webscorer app running in the background when the Android device goes to sleep - either on its own, or when the screen is turned off by the user.  Chip detections will happen without the app visible.

On iOS, the Webscorer app must be visible in order to receive chip detections but iOS allows the screen to stay on continuously via Settings / Display & Brightness / Auto-Lock / Never.