When I start Discover all I get is a square outline (Home Discover) in top left hand corner of my screen which immediately disappears. 
Using Fedora 26.


Details
Executable: plasma-discover PID: 2408 Signal: Segmentation fault (11) Time: 14/07/2017 13:52:10

Thread 1 (Thread 0x7f1d05dde8c0 (LWP 2408)):
[KCrash Handler]
#6  0x00007f1cbf5e35fd in FlatpakBackend::setupFlatpakInstallations(_GError**) () from /usr/lib64/qt5/plugins/discover/flatpak-backend.so

Regards
Mike
#7  0x00007f1cbf5e9a38 in FlatpakBackend::FlatpakBackend(QObject*) () from /usr/lib64/qt5/plugins/discover/flatpak-backend.so
#8  0x00007f1cbf5ec6bb in FlatpakBackendFactory::newInstance(QObject*, QString const&) const () from /usr/lib64/qt5/plugins/discover/flatpak-backend.so
#9  0x00007f1d0512f427 in DiscoverBackendsFactory::backendForFile(QString const&, QString const&) const () from /usr/lib64/plasma-discover/libDiscoverCommon.so
#10 0x00007f1d0512fabb in DiscoverBackendsFactory::backend(QString const&) const () from /usr/lib64/plasma-discover/libDiscoverCommon.so
#11 0x00007f1d0512ff27 in DiscoverBackendsFactory::allBackends() const () from /usr/lib64/plasma-discover/libDiscoverCommon.so
#12 0x00007f1d0511ea0a in ResourcesModel::registerAllBackends() () from /usr/lib64/plasma-discover/libDiscoverCommon.so
#13 0x00007f1d0513fa15 in ResourcesModel::qt_static_metacall(QObject*, QMetaObject::Call, int, void**) () from /usr/lib64/plasma-discover/libDiscoverCommon.so
#14 0x00007f1d01d5e199 in QObject::event(QEvent*) () from /lib64/libQt5Core.so.5
#15 0x00007f1d02d84d9c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /lib64/libQt5Widgets.so.5
#16 0x00007f1d02d8c3d4 in QApplication::notify(QObject*, QEvent*) () from /lib64/libQt5Widgets.so.5
#17 0x00007f1d01d35b8b in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /lib64/libQt5Core.so.5
#18 0x00007f1d01d37d6b in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () from /lib64/libQt5Core.so.5
#19 0x00007f1d01d84c73 in postEventSourceDispatch(_GSource*, int (*)(void*), void*) () from /lib64/libQt5Core.so.5
#20 0x00007f1cfa205247 in g_main_context_dispatch () from /lib64/libglib-2.0.so.0
#21 0x00007f1cfa2055e8 in g_main_context_iterate.isra () from /lib64/libglib-2.0.so.0
#22 0x00007f1cfa20567c in g_main_context_iteration () from /lib64/libglib-2.0.so.0
#23 0x00007f1d01d84cef in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /lib64/libQt5Core.so.5
#24 0x00007f1d01d34b8a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /lib64/libQt5Core.so.5
#25 0x00007f1d01d3c7dc in QCoreApplication::exec() () from /lib64/libQt5Core.so.5
#26 0x000055d0458746c0 in main ()