singleTask launch mode is not working

Having this weird problem of multiple instances of my activity getting created even after specifying the launchMode as singleTask. Has anybody faced this issue ? Any pointers will be appreciated.

Below is how i have declared my activity in the manifest:

    <activity
    android:name="com.test.TestActivity"
        android:launchMode="singleTask">
     <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>

            <intent-filter>
                <action android:name="android.intent.action.SEND" />
                <action android:name="android.intent.action.SEND_MULTIPLE" />

                <category android:name="android.intent.category.DEFAULT" />
                <data android:mimeType="*/*" />
            </intent-filter>
</activity>

And this is how i am launching my activity while it is still in foreground:

Intent sendIntent = new Intent();
        sendIntent.setAction(Intent.ACTION_SEND);
        sendIntent.putExtra(Intent.EXTRA_TEXT, sharedText);
        sendIntent.setType("text/plain");
        activity.startActivity(Intent.createChooser(sendIntent, "Share"));

Android version that i am testing it on is 5.1.1

So it seems the issue is with device. On emulator and other devices with same android version singleTask works just fine.