Cordova - XHR Requests on Android work in Emulator, but not on Phones

so I have an existing app that has been on the app store for quite some time, as of 3 days ago I was getting more support enquiries saying my app could not connect to my service.

Now it has finally happened to me on my Android devices - everything works perfectly for iOS, and perfectly for Android on Emulator - but nothing in the real world.

I have looked as far as I can by step-debugging with Cordova and it passes the whitelist test fine. My very first XHR request works fine, but subsequent ones always fail until I completely close the app and re-open.

I am using cordova-plugin-whitelist@1.3.4 - I have also tried cordova-plugin-whitelist@1.0.0

My Content-Security-Policy looks like this

<meta http-equiv="Content-Security-Policy" content="default-src * 'self' gap:; img-src http://*.my-site.com.au https://*.my-site.com.au https://*.my-site.com http://*.my-site.com https://*.googleusercontent.com http://*.googleapis.com  https://google.com https://*.google.com https://*.googleapis.com https://*.gstatic.com 'self' data:; style-src http://*.googleapis.com https://*.googleapis.com 'self' 'unsafe-inline'; script-src 'self' https://*.googleapis.com http://*.googleapis.com http://maps.google.com http://*.gstatic.com https://*.gstatic.com https://maps.google.com 'unsafe-inline' 'unsafe-eval'">

My Cordova config has

<allow-navigation href="*" />
<allow-navigation href="http://*/*" />
<allow-navigation href="https://*/*" />

I have tried adding/removing/replacing the above/every combination with <access origin="*" /> but no luck.

My XHR response always looks like the following

xhr.responseUrl = "http://my-site.com/?d=12343902i49"
xhr.status = 0
xhr.responseText = ""

I have step-debugged the XHR request as far as I could have in the Cordova Plugin, by step debugging out of the Whitelist.java but everything returns fine and it makes it successfully to the line

// If we don't need to special-case the request, let the browser load it.
return null;

of function

WebResourceResponse shouldInterceptRequest(WebView view, String url)

in org.apache.cordova.engine.SystemWebViewClient.java

My Android Manifest has the following

<uses-sdk android:minSdkVersion="19" android:targetSdkVersion="28" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_INTERNAL_STORAGE" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-feature android:name="android.hardware.location.gps" />
<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS" />
<uses-permission android:name="android.permission.READ_PHONE_STATE" />
<uses-permission android:name="android.permission.RECORD_VIDEO" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.FLASHLIGHT" />
<uses-feature android:name="android.hardware.camera" android:required="true" />
<uses-permission android:name="android.permission.WAKE_LOCK" />
<uses-permission android:name="android.permission.VIBRATE" />

I am using Cordova@8.0.0, Cordova platform Android@8.0.0

I've spent several hours trying to dig deeper, what am I missing here? Any help would be greatly appreciated!

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