How to fix lost data with android

I’ve received a lot of feedback from android users that they lost the player data suddenly and started game from initial…This issue tend to happen at update via google play market.
I guess this issue came after I imported some plugins and changed android manifest to add permissions.

Android OS : happen with 4.2, 5.0, 6.0
Unity : 5.5.0p4
Way to store data : Playerprefs with Writing PlayerPrefs, Fast - PreviewLabs
Permission in Manifest for Plugin :

Is there someone who faced same issue?
Please share your solution or hint with me.

You should try Script Serialization Unity - Manual: Script serialization
and Recorded Video Session: Quiz Game 2 - Unity Learn

This is probably the most popular way of dependably saving data.