Angularfire2 Not Saving Using Real Device

I added Facebook Login with Firebase and Angularfire2 to save data to Realtime Database.
Everything works fine using cordova run browser but not working on real device.
No error has been thrown. I can fetch all the data from Facebook really fine, I can even save and retrieve data from Firebase on other features of the app I am creating but the only thing that doesn’t work is saving after logging into Facebook. The saving part is not being triggered.

I also tried to create a new application, installed all the plugins and checked all the codes before copying and pasting them to the newly created app but still got the same results.

It is quite weird because I have the same feature with the previous apps I developed and they are all working fine. They almost have the same codes.

My question is: has anyone experienced the same? Any insights? Thanks!!!

Here is my ionic info:

@ionic/cli-utils : 1.19.2
ionic (Ionic CLI) : 3.20.0

global packages:

cordova (Cordova CLI) : 8.0.0

local packages:

@ionic/app-scripts : 3.1.10
Cordova Platforms  : android 7.0.0 browser 5.0.3
Ionic Framework    : ionic-angular 3.9.2


Node : v8.11.2
npm  : 5.6.0
OS   : Windows 10

Environment Variables:

ANDROID_HOME : C:\Android;C:\Android\sdk;C:\Android\sdk\platforms;C:\Android\sdk\platform-tools;C:\Android\sdk\tools;C:\Android\sdk\tools\bin;


backend : legacy