To reproduce:
1. Open user's attached project
2. Build for Android (make sure Google Play Games Account is set up)
3. When in app, click Authorize to conenct
4. Click the Show Overlay button and follow the procedure of GooglePlay Games
5. When recording layout is ready, press record. After it started recording lock the device with the Power button
6. Wait a few seconds and press the power button again to unlock the device

Expected: applicaton resumes activity
Actual: application is frozen

Reproduced in: 2017.1.5f1, 2017.2.3p3, 2017.4.9f1, 2018.1.9f1, 2018.2.4f1, 2018.3.0a8

Note1: The issue does not reproduce if screen lock is enabled, which probably wakes up the phone properly. Currently it seems that the device is not being awoken by simply unlocking with power button
Note2: getting a 100% reproduction on Xiaomi Mi 5, Mi 4i, Samsung Galaxy S6 edge

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Play Games Plugin for Unity bug report:
https://github.com/playgameservices/play-games-plugin-for-unity/issues/2221