Android app onStartup - White screen

Question

The well known issue of onStartup white screen appears with my app too (only since yesterday), but am unable to resolve with any suggestion as read in following threads:

1. How to remove the white screen while my app loads?
2. How to remove white screen while loading android application?
3. Android - Prevent white screen at startup
4. How To fix white screen on app Start up?
5. Instant run in Android Studio 2.0 (how to turn off)

and few more.

Not just onStartup, there are also some intermittent white screen for 5-10 seconds in between. This is happening both with build and release build.

Following is the code I'm using:

styles.xml:

<style name="Theme.Transparent" parent="Theme.AppCompat.Light.NoActionBar">
    <item name="android:windowNoTitle">true</item>
    <item name="android:windowActionBar">false</item>
    <item name="android:windowFullscreen">true</item>
    <item name="android:windowContentOverlay">@null</item>
    <item name="android:windowIsTranslucent">true</item>
</style>

Manifest:

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:hardwareAccelerated="true"
    android:theme="@style/AppTheme">

    <activity
        android:name=".MainPlayer"
        android:configChanges="orientation|keyboardHidden|screenSize"
        android:theme="@style/Theme.Transparent"></activity>

    <activity
        android:name=".RegisterActivity"
        android:configChanges="orientation|keyboardHidden|screenSize"
        android:theme="@style/Theme.Transparent">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>

    <receiver
        android:name="com.blynq.app.services.BootReceiver"
        android:permission="android.permission.RECEIVE_BOOT_COMPLETED"
        android:theme="@style/AppTheme">
        <intent-filter>
            <action android:name="android.intent.action.SCREEN_ON" />
            <action android:name="android.intent.action.BOOT_COMPLETED" />
            <action android:name="android.intent.action.MY_PACKAGE_REPLACED" />
        </intent-filter>
    </receiver>

</application>

This issue was not there until yesterday. Have not update Android Studio too since yesterday. Currently I am using Android Studio 2.1.1.

In dire need for a solution, would be greatly thankful for help of any sort in this regard ?