PlayerPrefs doesn't work from Play Store install, but does from editor/APK?

Help, PlayerPrefs doesn't seem to work and can't figure out why.

I have a simple game that starts with:

void Start()
{

if (PlayerPrefs.GetInt("IsReturningUser") == 1)
{
ScoreLabel.text = "Welcome back, friend!";
}
else
{
PlayerPrefs.SetInt("IsReturningUser", 1);
ScoreLabel.text = "Welcome new player";
}
When testing on my Android device from Unity Editor (build and run while connected) it works as intended - when I return to app second time it detects I'm returning.

However when I published the same code to Google Play store and clean installed from there, it never detects I'm a returning user when I return to app the second time.

Also strange, while it doesn't work on my Android phone, on my wife's phone installed from the Play Store it does detect as a returning user when she opens it the second time.

Any ideas?

Unity 5.3.6 My phone - Redmi Note 3, Android 6.0.1 MIUI 8.2 Stable Wife phone - OnePlusX

 

Answering my own question - turns out player prefs only saved when an exit procedure is triggered, but on my phone I was force closing it which I guess skips that. Solution was to write it manually each time values changed.