PandaBear123

> 7.5.1. Partner User Location. Any Partner Users that Partner Enlists or provides access to the Interoperable Messaging Services must be located and remain in the EEA. Without limiting Section 11 (Warranties), Partner represents and warrants that it will only (i) Enlist and (ii) enable access to the Interoperable Messaging Services by Partner Users that Partner independently validates are located in the European Economic Area, (i.e., a Partner User must be present within the European Economic Area within any consecutive sixty (60) calendar day period). If WhatsApp detects or otherwise has reasonable grounds to suspect a Partner User Enlisted to receive the Interoperable Messaging Services is not located in the European Economic Area or is no longer located in the EEA, WhatsApp reserves the right to immediately suspend such Partner User(s) from accessing the Interoperable Messaging Services, and if multiple violations are detected, Partner shall remedy Partner's location validation procedures to ensure compliance with the terms of this Agreement.

Looks like interoperability is geo-fenced to Europe only.

Do you happen to be using Verizon Fios and have IPv6 enabled? Apparently they had some underlying issues and disabling IPv6 fixed this for me.