Who I have the same questioned this topic

HI georob,

To add to Weth's feedback, make sure that you are SUBSCRIBED to Integrated Messaging, or the wifi function in the app won't work.

INTEGRATED MESSAGING: Launch Verizon Messages; go to Settings – under integrated Messaging feature, If you ARE Subscribed , you will see the Unsubscribe option. If NOT subscribed,   go ahead and subscribe. 

If every you find that you are kicked off of the wifi texting, TURN ON DATA and get on a Network; unsubscribe and re-subscribe to Integrated Messaging. You'll get a new PIN to use. This will re-activate the wifi function in the app.

Thanks,

ALIEM_VERIZONMESSAGES