I just received my glasses and I also can't get the WhatsApp POV sharing to work, the glasses icon just doesn't show up. The connection to Instagram is still working fine though.
Also according to the WhatsApp FAQ, you don't even need the connection in the Meta View app to WhatsApp for this to work, so it shouldn't be related to that:
You can also share your view from your glasses camera during a WhatsApp audio or video call. You can do this by double tapping the physical capture button on glasses during a call.You can use this feature even if you haven't linked WhatsApp in the Meta View app. To enable sharing your view, tap the glasses icon during your next video call for instructions.
