QLowEnergyService signals never called on WinRT

Calling QLowEnergyService::writeDescriptor(), readDescriptor() etc. results in warning spam, like this:
QObject::connect: Cannot queue arguments of type 'QLowEnergyDescriptor' (Make sure 'QLowEnergyDescriptor' is registered using qRegisterMetaType().

I can confirm that these functions do work, as these warning appear after calling "emit" in all of these functions in qtconnectivity/src/bluetooth/qlowenergycontroller_winrt.cpp, but signals never really get anywhere.

Tested against both 5.8.0 Beta, and snapshot of 5.8.0 RC (build 654).