The issue is resolved in Threatpulse client connector version 1.6.10500.0 or later. As of this update (April 17, 2013), the current client connector is version 1.6.11300.0. Blue Coat recommends using the most current client connector.
The issue is that the Blue Coat drivers are not compatible with the new driver model used by the 3G WWAN cards. Other vendors, such as Cisco VPN, also have the same issue. The problem and reasons for the problem are explained at a third-party site: http://www.customsoftwareframeworks.com/blog/fix-vpn-problems-cellular-win7 .