When I press the hotkey to capture a fullscreen screenshot, plasma-shell appears to hang. What's actually happening, is that Spectacle is flooding it with notifications at high rate:

org.kde.plasma.notifications: Failed to generate job text for job with following properties:
org.kde.plasma.notifications:   processedFiles = 0 , totalFiles = 0 , current file name = "Screenshot_20190919_2-5192.png" , destination url string = ""
org.kde.plasma.notifications: label1 = "File" , value1 = "/home/bernie/Desktop/Screenshot_20190919_2-5192.png" , label2 = "" , value2 = ""
org.kde.plasma.notifications: Failed to generate job text for job with following properties:
org.kde.plasma.notifications:   processedFiles = 0 , totalFiles = 0 , current file name = "Screenshot_20190919_2-5193.png" , destination url string = ""
org.kde.plasma.notifications: label1 = "File" , value1 = "/home/bernie/Desktop/Screenshot_20190919_2-5193.png" , label2 = "" , value2 = ""


The number at the end of the filename keeps incrementing forever.

I captured a stacktrace of spectacle while this is happening:

#8  0x00007ffff7df6115 in KDynamicJobTracker::registerJob(KJob*) () from /lib64/libKF5KIOWidgets.so.5
#9  0x00007ffff7c2b349 in KIO::stat(QUrl const&, KIO::StatJob::StatSide, short, QFlags<KIO::JobFlag>) () from /lib64/libKF5KIOCore.so.5
#10 0x000055555557c8c1 in ExportManager::isFileExists(QUrl const&) const ()
#11 0x000055555557d131 in ExportManager::autoIncrementFilename(QString const&, QString const&, bool (ExportManager::*)(QUrl const&) const) ()
#12 0x000055555557eadd in ExportManager::getAutosaveFilename() ()
#13 0x0000555555580373 in ExportManager::doSave(QUrl const&, bool) ()
#14 0x0000555555584d8c in SpectacleCore::screenshotUpdated(QPixmap const&) ()
#15 0x00007ffff65b0ea0 in QMetaObject::activate(QObject*, int, int, void**) () from /lib64/libQt5Core.so.5
#16 0x00005555555788e6 in ImageGrabber::pixmapChanged(QPixmap const&) ()
#17 0x00005555555a4ecb in X11ImageGrabber::KWinDBusScreenshotHelper(unsigned long long) ()
#18 0x000055555557b453 in X11ImageGrabber::qt_metacall(QMetaObject::Call, int, void**) ()
#19 0x00007ffff6d9b68b in QDBusConnectionPrivate::deliverCall(QObject*, int, QDBusMessage const&, QVector<int> const&, int) () from /lib64/libQt5DBus.so.5
#20 0x00007ffff65b1bda in QObject::event(QEvent*) () from /lib64/libQt5Core.so.5
#21 0x00007ffff70bdaf6 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /lib64/libQt5Widgets.so.5
#22 0x00007ffff70c6e80 in QApplication::notify(QObject*, QEvent*) () from /lib64/libQt5Widgets.so.5
#23 0x00007ffff6586ad8 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /lib64/libQt5Core.so.5
#24 0x00007ffff6589a7b in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () from /lib64/libQt5Core.so.5
#25 0x00007ffff65dbe27 in postEventSourceDispatch(_GSource*, int (*)(void*), void*) () from /lib64/libQt5Core.so.5