In Vugen 11.0x and earlier, it was possible to import a WSDL from Quality Center. After LoadRunner 11.5x the option is no longer available.
The Import from Quality Center feature on Vugen was built to support Service Test Manager (STM).
STM is not supported after ALM 11.5x, so the feature was not implemented in Vugen. To import a WSDL, you must first export it to an accessible file system.