Android - Start Activity on Phone Boot Not Working

Question

I'm trying to add a BroadcastReceiver to my program that will launch my MainActivity when the BOOT_COMPLETED action is detected.

I've tried everything here and here and it refuses to work. I am running Android 5.1.1, API 22.

AndroidManifest.xml

<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />

<!-- Declaring broadcast receiver for BOOT_COMPLETED event. -->
        <receiver
            android:name=".BootReceiver"
            android:enabled="true"
            android:exported="true"
            android:permission="android.permission.RECEIVE_BOOT_COMPLETED">
            <intent-filter>
                <action android:name="android.intent.action.BOOT_COMPLETED"/>
                <action android:name="android.intent.action.QUICKBOOT_POWERON"/>
                <category android:name="android.intent.category.DEFAULT"/>
            </intent-filter>
        </receiver>

In the <intent-filter>, I've tried using both BOOT_COMPLETED and QUICKBOOT_POWERON independently as well as in conjunction (as pictured) with no change in result.

BootReceiver.java

public class BootReceiver extends BroadcastReceiver {
    private final static String TAG = BootReceiver.class.getSimpleName();
    @Override
    public void onReceive(Context context, Intent intent) {

        Log.d(TAG, "BootReceiver has been called - attempting to launch MainActivity");

        Intent startMainActivityIntent = new Intent(context, MainActivity.class);
        startMainActivityIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        context.startActivity(startMainActivityIntent);
    }
}

EDIT: I was removing the app from multi-tasking before restarting the phone. If I start the activity and then restart the phone while it's running, it seems to still be there upon rebooting. However, attempting to open it results in a crash.