[scruffups]

Local IP Leak SOLVED:

Chrome (and maybe other browsers, too) no longer share local IP address. They share the mDNS address instead, which is often generated and registered locally by the browser. It's used only if the peers are on the same network. Else, it's useless but it used to be provided to all peers and malicious websites and they stopped doing that (speaking for those browsers that support mDNS)

Public IP Leak in VPN SOLVED:

In Chromium version 48+, you can set webRTCIPHandlingPolicy to default_public_interface_only which means that any VPN proxy will carry WebRTC media (over UPD if it supports UDP or else over TCP, which impacts quality of transmission)

Your VPN provider just has to provide a Chrome extension to do the above or advise you to do that yourself. That way, the VPN's proxy IP address is what's visible to STUN, not the user's public IP address.

There is also a more elaborate way around it, but the above should work.