Some phones have an option that automatically closes all apps when phone is on sleep mode. This prevents ACR from starting and recording when there is a call.
In order to avoid this issue, enable ACR notification and then find the power saving option on your phone, open it and add ACR to protected apps or disable optimization for ACR. It is usually under Phone battery settings.
This option might be called:
- "Power saving"
- "Batter optimization"
- "Battery usage"
- "App optimization"
Here are the screen shots from different phones showing power saving setting
Samsung ultra data saving:
Huawei Android 6:
Huawei Android 7:
XIAOMI has app lock feature in their MIUI Task manager, you need to lock ACR
Oneplus one/two/three Android 6/7:
Settings=>Apps=>Configure Apps=>Special Access=>Battery Optimization