When Showcase is started, and periodically while it is running, it will attempt to verify that it is a legally licensed product. The license validation for a local, node-locked license or a network floating license both use either he IPv4 or IPv6 network interface (referred to as a stack).
The license checkout process can take place over an IPv6 network, but the licensing component requires that the IPv4 network stack be enabled. This is referred to as a "dual-stack" configuration.
For Showcase to validate a license, ensure that both the IPv6 and IPv4 Internet Protocols (TCP/IP) are enabled in the Windows Network Connections properties. Showcase will not launch without the IPv4 stack enabled.