Blackview

System restrictions on Blackview phones have not been fully discovered yet. If you have any additional information, please let us know.

The guide we have is confirmed for BV6300Pro (Android 10).

Basic setting

1. System settings > Apps & Notifications

2. Choose Pomodoro app -> Advanced settings

3. Battery

4. Battery optimization

5. Expand the list to All applications

6. Set Pomodoro app to Don't optimize

This point is not confirmed to be helpful, but it was suggested by the technical support and also in some internet discussions.

1. Go to Overview (Recent apps menu)
> tap the Screwdriver and Wrench icon

2. Lock Pomodoro app in the White List

You can either whitelist Your app from the DuraSpeed, or disable it completely.

1. Settings > Smart Assist

2. DuraSpeed

3. Enable Pomodoro app, or Disable DuraSpeed for all apps

1. Run application Basic Service

2. App Manager

3. App auto start

4. Enable Pomodoro app

1. Run application Basic Service

2. Settings (top right corner)

3. Disable Intelligent power saving in sleep mode

Source: dontkillmyapp