To solve this issue, we can suggest you as follows:
1. Open the device Settings/ About phone(tablet)
2. Tap several times on Build number to activate Developer Options. If the Developer options is available in the Settings, you can skip this step
3. Open Developer Options => Media => Use AwesomePlayer => Switch on/off option
4. Go back to Piano+, run the app and check it out.
In case the solution does not work, please contact us at email@example.com; send us some basic information such as device model, Android OS, app version. Our team will work on it.