The last TODO has been converted into a bug, though it might end up being fixed internally by Vivox if they repro with testing.

Assets/Scripts/Vivox/VivoxSetup.cs

             {
                 ChannelId id = m_channelSession.Channel;
                 m_channelSession?.Disconnect(
-                    (result) => { m_loginSession.DeleteChannelSession(id); m_channelSession = null; }); // TODO: What about if this is called while also trying to connect?
+                    (result) => { m_loginSession.DeleteChannelSession(id); m_channelSession = null; });
             }
             foreach (VivoxUserHandler userHandler in m_userHandlers)
                 userHandler.OnChannelLeft();